How Pirates Prevented America from Adopting the Metric System: The Full Story
The United States' complicated relationship with the metric system stems from a historical series of missed opportunities and resistance to change. While much of the world has embraced the standardized decimal-based system of measurement, America continues to primarily use the US customary system in everyday life. This unique position has created challenges for international trade, scientific collaboration, and even space exploration.
The story of America's metric reluctance involves many fascinating elements—from Thomas Jefferson's early interest in the French system to a fateful Caribbean pirate encounter that derailed an early adoption attempt. Despite multiple legislative efforts throughout the 20th century and the fact that many American businesses and scientific institutions have internally converted to metric, the general public has maintained its attachment to feet, pounds, and miles.
Key Takeaways
America's resistance to the metric system began with a historical mishap involving privateers who intercepted the original metric standards en route from France.
Major American corporations and scientific institutions have already converted to metric to facilitate international business and prevent costly conversion errors.
Despite multiple legislative attempts to transition the country to metric standards, cultural attachment to customary measurements has prevented widespread public adoption.
Historical Context of US Metrication
The United States' relationship with the metric system began in 1793, shortly after the nation's founding. At that time, America faced challenges with inconsistent measurement standards across states, with New York using Dutch measurements while other states employed English-based or various European systems.
Thomas Jefferson, then Secretary of State and known for his appreciation of French culture, became interested in France's new decimal-based measurement system. He arranged for French scientist Joseph Dombey to bring metric standards to America—specifically a one-kilogram copper weight and a one-meter scale.
Unfortunately, Dombey's ship was blown off course during a storm. British privateers intercepted the vessel in the Caribbean, confiscated the metric standards, and imprisoned Dombey, who later died in captivity. This early setback significantly delayed American adoption of the metric system.
By the mid-1800s, the United States had largely settled on the US Customary System, based on British Imperial measurements. Despite this, Congress authorized metric usage in 1866 and provided states with metric standards, though public adoption remained limited.
The US became a signatory to the Meter Convention in 1875, an international treaty establishing metric standards. However, powerful industrial interests resisted the change, arguing it would be too costly to implement and harmful to American infrastructure.
Interestingly, since 1893, all US measurements have been officially defined by their metric equivalents. A yard is technically defined as 0.9144 meters, not as 3 feet or 36 inches.
The mid-20th century saw increased globalization pushing countries toward metric adoption. While the UK switched in 1965 to access European markets, American efforts remained voluntary. The 1971 congressional recommendation for metric transition within a decade never materialized, and the Metric Conversion Act of 1975 merely encouraged rather than mandated the change.
Major American corporations like General Motors, IBM, Ford, and Xerox independently adopted metric standards for international competitiveness and cost savings, often well before the 1975 legislation. The scientific community also embraced metric measurements, especially after NASA's expensive mistake in 1999 when the Mars Climate Orbiter was lost due to unit conversion errors between metric and imperial measurements.
Subsequent legislative efforts failed to gain traction:
Omnibus Foreign Trade Act (1988)
Savings and Construction Act (1996)
High-End Computing Revitalization Act (2004)
Even Lincoln Chafee's 2016 presidential campaign, which boldly championed metric adoption, failed to generate substantial public support for change.
Today, America functions as a partially metric nation. Federal agencies must use metric units, and consumer products require metric labeling. Manufacturing increasingly employs metric standards, representing a gradual, ongoing transition rather than the wholesale conversion seen in other countries.
Thomas Jefferson and French Influence
Thomas Jefferson, serving as Secretary of State in 1793, recognized the need for standardized weights and measures across the newly formed United States. Each state had adopted different measurement systems—New York used Dutch measurements, while others followed English units or systems from Spain and France. This inconsistency created significant problems for interstate commerce.
Jefferson developed a strong affinity for French culture during his time in France. His admiration coincided with the French Revolution, during which France was implementing a new decimal-based measurement system.
Intrigued by the French approach, Jefferson requested that the United States explore adopting similar standards. French scientist Joseph Dombey was tasked with bringing two essential metric items to America: a copper one-kilogram weight (called a "grave") and a one-meter scale.
Dombey's journey took an unexpected turn when his ship encountered a storm, pushing it south toward the Caribbean. There, British privateers—government-sanctioned sailors legally permitted to attack enemy vessels—intercepted Dombey's ship. They confiscated the metric standards and imprisoned Dombey, who later died in captivity. The metric tools were subsequently sold at auction.
This unfortunate maritime incident significantly delayed America's potential adoption of the metric system. By the mid-1800s, the United States had largely settled on the U.S. Customary System of measurements, derived from the British Imperial system.
The Tale of Joseph Dombey
In 1793, the newly formed United States faced challenges with standardizing weights and measurements. Each state operated differently—New York used a Dutch system, while other states relied on English units, creating complications for interstate commerce. Thomas Jefferson, then Secretary of State and an admirer of French culture, became interested in France's new decimal-based measurement system being implemented during their revolution.
Jefferson arranged for French scientist Joseph Dombey to bring two metric prototypes to America: a copper one-kilogram weight (called a "grave") and a one-meter scale. This journey might have changed American measurement history forever.
Unfortunately, Dombey's ship encountered a storm that pushed it off course into Caribbean waters. There, British privateers—government-sanctioned ship raiders—intercepted the vessel. They captured Dombey, confiscated the metric standards, and imprisoned him, hoping to secure a ransom. Tragically, Dombey died while in captivity, and the metric prototypes were sold at auction.
This maritime misfortune derailed America's early opportunity to adopt the metric system. By the mid-1800s, the United States had settled on the US customary system, based on Britain's imperial measurements. Despite this setback, Congress authorized metric system use in 1866 and provided metric standards to states, but public adoption remained limited.
Many Americans preferred the US customary system for its relatable qualities. A foot approximates an actual foot length, while an inch resembles a thumb width—tangible references that people found easier to understand than abstract metric units.
The United States made repeated attempts to join the international metric community:
1875: Signed the Meter Convention treaty establishing metric standards
1893: Officially defined all US measurements by metric equivalents
1971: Congress recommended metric conversion within 10 years
1975: Passed the Metric Conversion Act (voluntary, not mandatory)
1988, 1996, 2004: Further legislation attempted to advance metric adoption
Despite legislative efforts, industrial opposition presented significant barriers. Powerful manufacturers argued that conversion costs would be prohibitive and harmful to American infrastructure. Nevertheless, major corporations like GM, Ford, IBM, and Xerox independently adopted metric standards to remain competitive globally.
Today, America is technically metric in many crucial areas. Federal agencies must use metric units, consumer products require metric labeling, and manufacturing often employs metric measurements. The transition continues gradually, suggesting America may eventually complete its long-delayed metric journey—even without the help of Joseph Dombey's lost prototypes.
Pirate Interference and Metric System Delay
The United States' hesitant relationship with the metric system dates back to 1793, when the young nation was establishing standardized weights and measures. Thomas Jefferson, serving as Secretary of State and known for his admiration of French culture, was intrigued by France's new decimal-based measurement system being implemented during their revolution.
Jefferson arranged for French scientist Joseph Dombey to bring metric standards to America. Dombey traveled with two critical items: a copper weight representing one kilogram (called a "grave") and a one-meter scale. These objects were intended to help standardize American measurements.
What happened next changed American measurement history. Dombey's ship encountered a storm and drifted too far south into Caribbean waters. British privateers—government-sanctioned ships authorized to attack enemy vessels—intercepted Dombey's ship. They seized the metric standards and imprisoned Dombey, hoping to collect a ransom.
Tragically, Dombey died in prison, and the metric standards were sold at auction. This pirate encounter effectively derailed America's first official introduction to the metric system.
By the mid-1800s, America had largely adopted the US customary system, derived from British imperial measurements. Despite this, Congress authorized metric system use in 1866 and provided states with metric standards, but public adoption remained limited.
Many Americans preferred the customary system because:
It seemed more relatable (a foot approximates a human foot)
It offered tangible reference points (an inch roughly equals thumb width)
It provided consistency while metric standards occasionally fluctuated
America continued making efforts toward metric adoption:
1875: Signed the Meter Convention international treaty
1893: Officially defined all US measurements via metric equivalents
1971: Congress recommended complete transition within a decade
1975: Passed the Metric Conversion Act (encouraged but didn't mandate use)
Industrial resistance presented significant obstacles. Powerful business interests argued that switching would be too expensive and harmful to American infrastructure. Ironically, many major American corporations like GM, Ford, IBM, and Xerox independently adopted metric standards to remain globally competitive.
The scientific community also recognized metric benefits, especially after NASA's costly mistake. In 1999, the Mars Climate Orbiter crashed into the Martian atmosphere—a $125 million failure resulting from confusion between metric and imperial measurements.
Despite several legislative attempts in 1988, 1996, and 2004, metric adoption remains incomplete. During the 2016 presidential campaign, candidate Lincoln Chafee made metric conversion a core platform issue, but his campaign gained little traction.
Today, America functions as a partially metric country. Federal agencies must use metric measurements, and consumer products require metric labeling. The transition continues gradually, suggesting that complete adoption may eventually occur, even if progress moves forward only millimeter by millimeter.
Adoption of the US Customary System
The United States' reluctance to fully embrace the metric system has deep historical roots dating back to the late 18th century. In 1793, Thomas Jefferson, then Secretary of State, recognized the need for standardized weights and measures as different states were using various systems—New York followed Dutch measurements, while others used English units.
Jefferson's interest in France's new decimal-based system led him to request support from the French. Scientist Joseph Dombey was sent to America with two metric standards: a one-kilogram copper weight and a one-meter scale. Unfortunately, Dombey's journey was disrupted when British privateers intercepted his ship in the Caribbean.
The privateers—government-sanctioned ship attackers—captured Dombey and seized the metric standards. Dombey died in prison, and the metric items were auctioned off, derailing America's first attempt at metric adoption.
By the mid-1800s, the United States had settled on the US Customary System, derived from Britain's imperial measurements. Congress authorized metric usage in 1866 and provided states with metric standards, but public resistance remained strong. Many Americans preferred the tangible nature of customary units—a foot approximating the length of a human foot, an inch roughly the width of a thumb.
Several attempts at metric conversion followed:
1875: The US signed the Meter Convention, an international metric standards treaty
1893: Official US measurements were defined by metric equivalents
1971: Congress recommended transitioning to metric within a decade
1975: The Metric Conversion Act encouraged but didn't mandate metric usage
1988: The Omnibus Foreign Trade Act attempted to advance metric adoption
1996: The Savings and Construction Act included metric provisions
2004: The High-End Computing Revitalization Act made another attempt
Industrial pushback created significant obstacles throughout these efforts. Powerful business interests argued that converting would be too costly and harmful to American infrastructure. Ironically, many major American corporations—including GM, Ford, IBM, and Xerox—independently adopted metric standards before 1975 to facilitate international trade.
The scientific community's support for metric increased after NASA's 1999 Mars Climate Orbiter disaster. The $125 million spacecraft crashed because Lockheed Martin engineers provided thruster measurements in pounds while NASA used metric newtons.
In practice, the US has partially embraced metric. Federal agencies must use metric units, and consumer products require metric labeling. Manufacturing increasingly employs metric standards, indicating a slow but steady progression toward international measurement alignment.
Metric System Adoption Efforts in the United States
The Metric Legislation of 1866
The United States made its first official recognition of the metric system in 1866. Congress passed legislation that authorized the use of metric measurements throughout the country. As part of this initiative, each state received its own set of metric weights and measures. Despite this official authorization, the law didn't mandate the switch to metric, merely permitted its use. Public reception was lukewarm at best, as many Americans found the U.S. customary system more relatable and intuitive.
The Meter Convention Treaty
In 1875, the United States took another step toward metric adoption by signing the Meter Convention. This international treaty established a framework for creating standardized metric measurements across participating nations. The agreement created a system of consistent metric standards that would be recognized globally. Though the U.S. was a signatory to this important treaty, the agreement didn't translate into widespread domestic adoption of the metric system.
Industrial Resistance to Metric Conversion
American industry played a significant role in blocking complete metric conversion. Powerful industrialists and business leaders argued against metric adoption for several reasons:
Cost concerns: The expense of retooling factories was deemed prohibitive
Infrastructure challenges: Existing systems were built around customary units
Workforce training: Retraining workers would require significant investment
These economic arguments proved persuasive despite international pressure. Interestingly, many large American corporations eventually adopted metric internally despite the national resistance. Companies like GM, Ford, IBM, and Xerox switched to metric measurements decades ago, recognizing the efficiency and international advantages.
Defining American Units Through Metric Standards
By 1893, the United States had taken the pragmatic step of defining all its customary measurements by metric standards. This created an unusual situation where:
A yard became officially defined as 0.9144 meters
Pounds, inches, and miles were all standardized by their metric equivalents
The U.S. maintained its customary units while anchoring them to metric definitions
This approach allowed the U.S. to maintain consistency with international standards while preserving familiar units for everyday use. The scientific community has largely embraced metric measurements, particularly after expensive mistakes like NASA's 1999 Mars Climate Orbiter crash—a $125 million failure caused by confusion between metric and customary units in different components of the mission.
Global Economic Factors
The adoption of measurement systems has significant economic implications worldwide. Countries often make measurement decisions based on trade relationships and economic partnerships. In 1965, the United Kingdom switched to the metric system primarily to gain better access to European markets, demonstrating how economic incentives drive standardization.
Large American corporations recognized the financial benefits of metric conversion long before government mandates. Companies like Xerox, General Motors, IBM, and Ford voluntarily adopted metric standards to remain competitive in international markets. These businesses saved millions of dollars through standardization, proving the economic advantage of metric adoption in global commerce.
The fragmented measurement approach has occasionally resulted in costly errors. In 1999, NASA lost the Mars Climate Orbiter—valued at $125 million—when thruster measurements in metric Newtons were misinterpreted by ground control using pounds. This expensive mistake highlighted the financial risks of maintaining dual measurement systems.
American industries have shown mixed responses to metric conversion:
Sector Response to Metric System Large Corporations Generally embraced metric for global competitiveness Scientific Community Strongly favors metric for precision and standardization Manufacturing Increasingly metric, especially for international products Consumer Markets Maintains dual labeling requirements
Several U.S. legislative attempts to standardize measurements have faced resistance from certain industrial sectors. Powerful manufacturing interests historically argued that conversion costs would be prohibitively expensive and potentially harmful to American infrastructure.
Despite resistance, practical implementation continues gradually. Federal agencies now must use metric measurements, and consumer products require metric labeling. This incremental approach balances tradition with the economic necessities of global trade and standardization.
US Businesses and the Metric System
The United States has a complicated relationship with the metric system. While the nation officially recognizes metric measurements, it hasn't fully embraced them in everyday life. American businesses, however, have taken a different approach.
Major corporations recognized the financial benefits of adopting metric standards decades ago. Companies like Xerox, GM, IBM, and Ford switched to metric measurements well before 1975, saving millions of dollars in the process. These industry leaders understood that global commerce required metric compatibility.
The scientific and engineering communities have also pushed for metric adoption. A costly reminder of the importance of standardized measurements came in 1999 when NASA's Mars Climate Orbiter disintegrated in the Martian atmosphere. This $125 million mistake occurred because NASA was using metric units while Lockheed Martin engineers used imperial measurements.
From a technical standpoint, America is already largely a metric country:
Federal agencies must use metric measurements
Consumer products require metric labeling
Manufacturing processes utilize metric standards
Despite multiple legislative attempts to accelerate metric adoption—including the Metric Conversion Act (1975), the Omnibus Foreign Trade Act (1988), and the High-End Computing Revitalization Act (2004)—widespread public conversion remains elusive. Business interests have sometimes opposed these changes, with some industrialists arguing that switching would be too expensive and harmful to American infrastructure.
The metric system did find an unlikely political champion in 2016 when Lincoln Chafee, former Rhode Island governor and senator, made metric adoption a core element of his presidential campaign platform. His bold stance on internationalism through metric conversion failed to resonate with voters.
Scientific Community and NASA's Oversight
The scientific community in the United States has long recognized the benefits of the metric system. Major American companies like Xerox, GM, IBM, and Ford switched to metric measurements decades ago, seeing the financial advantages of standardization for international business operations.
NASA experienced a costly reminder of the importance of consistent measurement systems in 1999. The Mars Climate Orbiter mission ended in failure when the spacecraft crashed into the Martian atmosphere due to a unit conversion error. The thrusters on the orbiter were calibrated in metric Newtons, while ground control was using pounds.
This measurement discrepancy resulted in the loss of approximately $125 million and years of scientific work. The blame was shared between NASA and engineers at Lockheed Martin who failed to ensure consistent units across all systems and operations.
Despite such high-profile failures, federal progress toward full metric adoption has been slow. Various legislative attempts to encourage metric usage, including the Omnibus Foreign Trade Act (1988), the Savings and Construction Act (1996), and the High-End Computing Revitalization Act (2004), have had limited success in changing everyday American measurement practices.
Technically, the United States is already a metric country in many official capacities:
All federal agencies are required to use metric measurements
Consumer products must include metric measurements on packaging
Manufacturing standards incorporate metric specifications
The transition continues gradually, with scientific and business sectors leading the way toward full metric adoption.
Legislative Efforts to Implement Metric
The United States has made several attempts to adopt the metric system through legislation. These efforts span decades and demonstrate both progress and resistance to changing measurement standards in America. While many sectors of American business and science have embraced metric units, complete national adoption remains elusive.
Metric Conversion Act of 1975
The Metric Conversion Act marked Congress's first major legislative push toward metrication. This law encouraged rather than mandated the use of the metric system in the United States. The voluntary nature of the act ultimately limited its effectiveness, as many Americans continued using customary measurements in their daily lives.
Key aspects of the 1975 legislation:
Created a U.S. Metric Board to coordinate voluntary conversion
Declared metric as the "preferred" system for trade and commerce
Lacked enforcement mechanisms or conversion deadlines
Allowed industries to determine their own adoption timelines
Omnibus Foreign Trade Act of 1988
As global commerce expanded, Congress tried again with provisions in the 1988 Omnibus Foreign Trade Act. This legislation designated the metric system as the preferred measurement standard for U.S. trade and commerce. Despite these efforts, widespread adoption remained limited due to the continuing voluntary approach.
The act required federal agencies to use metric in procurement, grants, and business activities by the end of 1992. Many large American corporations had already independently switched to metric measurements by this time, including:
Companies Using Metric Industry IBM Technology Ford Automotive General Motors Automotive Xerox Business Equipment
Savings in Construction Act of 1996
This legislation focused specifically on the construction industry, which had been particularly resistant to metric conversion. The act eliminated requirements for federal construction projects to use metric measurements exclusively. This represented a step back from previous conversion efforts in a key economic sector.
High-Performance Computing Act of 1996
The High-Performance Computing Act included provisions related to metric usage in scientific and technological applications. This act recognized the importance of standardized measurements in advanced computing and research. Technical fields in America had already widely adopted metric units, especially after high-profile failures caused by measurement confusion.
A notable example occurred in 1999 when NASA lost the $125 million Mars Climate Orbiter. The spacecraft crashed into the Martian atmosphere because Lockheed Martin engineers provided thrust measurements in pounds while NASA's navigation team used metric newtons.
Metrication Advocacy and Lincoln Chafee
Political support for complete metric conversion has been limited in recent decades. During the 2016 presidential campaign, former Rhode Island governor Lincoln Chafee made metric adoption a central policy position. His platform called for the United States to "join the rest of the world and go metric" as a bold embrace of internationalism.
Chafee's metric advocacy failed to resonate with voters, and his campaign ended quickly. Despite limited political momentum, America continues gradual metrication through:
Federal agency requirements to use metric units
Mandatory metric information on consumer products and food packaging
Widespread metric adoption in manufacturing and international business
Current State of Metrication in the United States
The United States occupies a unique position regarding metric adoption, operating in what could be described as a state of partial metrication. Despite multiple legislative attempts to fully embrace the metric system, the transition remains incomplete as of 2025.
From a technical standpoint, America already functions as a metric country in many respects. Federal agencies must use metric units in their operations, and consumer products are required to display metric measurements on packaging. Most major American corporations—including automotive manufacturers like Ford and GM, and technology giants such as IBM and Xerox—switched to metric decades ago to remain competitive in global markets.
The scientific community strongly favors metric usage, particularly after costly errors like NASA's 1999 Mars Climate Orbiter disaster. This $125 million mission failed when Lockheed Martin engineers provided thruster measurements in pounds while NASA expected metric newtons, resulting in the spacecraft's destruction upon reaching Mars.
Despite these advances, public adoption remains limited. The U.S. continues to use the customary system for everyday measurements:
Measurement Type U.S. Customary Metric Equivalent Length Inch, foot, yard, mile Millimeter, centimeter, meter, kilometer Weight Ounce, pound, ton Gram, kilogram, metric ton Volume Fluid ounce, cup, pint, gallon Milliliter, liter
Congress has made multiple attempts to encourage metric adoption:
1866: First authorization of metric system use
1971: Recommendation for metric transition within 10 years
1975: Metric Conversion Act (encouraged but didn't require adoption)
1988: Omnibus Foreign Trade Act
1996: Savings and Construction Act
2004: High-End Computing Revitalization Act
None of these initiatives achieved complete conversion. Even a 2016 presidential campaign platform by Lincoln Chafee that prominently featured metric adoption failed to generate significant public support.
The persistence of customary measurements in the U.S. stems partially from their perceived practicality—a foot approximates an actual foot length, while an inch roughly corresponds to thumb width. These tangible references have maintained their appeal among the American public despite the global predominance of metric units.
Conclusion
The metric system debate in the United States continues to evolve gradually. Despite multiple legislative attempts since the 1970s, including the Metric Conversion Act of 1975 and several subsequent bills, full adoption remains elusive. Major corporations like Ford, GM, and IBM recognized the financial benefits and embraced metric standards decades ago.
The scientific community also understands metric's importance, particularly after costly mistakes like NASA's 1999 Mars Climate Orbiter crash—a $125 million error resulting from unit conversion confusion. Technically, America has already partially converted, with federal agencies required to use metric units and product packaging displaying metric measurements alongside imperial units.
The journey toward metric adoption in the US progresses incrementally. While historical resistance stems from industrial concerns about conversion costs and cultural attachment to familiar measurements, the practical benefits of international standardization remain compelling. What are your thoughts on metric adoption? Should America complete the transition, or is the current dual-system approach sufficient?
