question: Why did the US Never get on board with the rest of the world with the metric system?
comment: They tried. The Metric Conversion Act was signed in December of 1975, but the only issue was, it was voluntary. It was never really enforced, and it only stated that metric was the preferred way to do stuff. With no pressure to switch, nobody switched
passages: One of the actions taken by Congress was to permit the use of the metric system in trade (1866), made at the height of the metrication process in Latin America. Other actions were to ratify the Metre Convention in 1875 and under the Mendenhall Order of 1897, to redefine the pound and the yard in terms of the International Prototype Kilogram and the International Prototype Metre respectively.
   Britain was initially involved in the development of the metric system, and the US was among the 17 initial signatories of the Metre Convention in 1875. Yet in spite of enthusiastic support for the new system by intellectuals such as Charles Dickens, these two countries were particularly slow to implement it.
   In the years that followed the passing of the 1878 Act, the standard imperial yard was found to be shrinking at a rate, confirmed in 1950, to be nearly one part per million every 30 years. On the other hand, the international prototype metre, manufactured from a platinum-iridium alloy rather than brass by a British firm, which in 1889 replaced the "metre des archives" as the standard for the metre, was found to be more stable than the standard yard. Both the United States and the United Kingdom, as signatories of the Metre Convention, took delivery of copies of both the standard metre and the standard kilogram. The "Mint pound" was also found to be of poor workmanship.
   By the end of the Second World War, the standards laboratories of Canada, Australia, New Zealand and South Africa also had their own copies of the pound and the yard. These legal and technical discrepancies, described by McGreevy (pg 290) as being "unsound" led to the Commonwealth Science Conference of 1946. proposing that the Commonwealth countries and the United States should all redefine the yard and the pound in terms of an agreed fraction of the metre and kilogram respectively. Agreement was reached by the standards laboratories in 1960 to redefine the yard and the metre as 
   It took more than thirty years before Giorgi's work was accepted in practice by the IEC.
  
  Section::::Measurement systems before the war.:Systems of measurement in the industrial era.
   The Metric Act of 1866 was passed by Congress and allowed, but did not require, the use of the metric system. Included in the law was a table of conversion factors between the traditional and metric units. The U.S. Coast and Geodetic Survey Office of Weights and Measures had on hand a number of metric standards, and selected the iron “Committee Meter” and the platinum "Arago Kilogram" to be the national standards for metric measurement; the standard yard and pound previously mentioned continued to be the standards for customary measurements. (Barbrow & Judson 1976, 10).
   The standardization of the yard in 1960 required not only agreement between the United States and the United Kingdom, but also of Canada, Australia, New Zealand and South Africa, all of whom had their own standards laboratories.
  
  Section::::United States customary units.
   Section::::1875 conference.:Reference standards.
  
  The conference was called to discuss the maintenance of international standards based on the existing French standards rather than using French standards which, at that time, were 70 years old and which, through wear and tear, might not be exactly the same as when they adopted in 1799.
   In 1805 a Swiss geodesist Ferdinand Rudolph Hassler brought copies of the French metre and kilogram to the United States. In 1830 the Congress decided to create uniform standards for length and weight in the United States. Hassler was mandated to work out the new standards and proposed to adopt the metric system. The Congress opted for the British Parliamentiary Standard from 1758 and the Troy Pound of Great Britain from 1824 as length and weight standards. Nevertheless the primary baseline of the US Coast Survey was measured in 1834 at Fire Island using four two-metre iron bars constructed after Hassler's specification in the United Kingdom and brought back in the United States in 1815. All distances measured in the US National Geodetic Survey were referred to the metre. In 1866 the United States Congress passed a bill making it lawful to use the metric system in the United States. The bill, which was permissive rather than mandatory in nature, defined the metric system in terms of customary units rather than with reference to the international prototype metre and kilogram. By 1893, the reference standards for customary units had become unreliable. Moreover, the United States, being a signatory of the Metre Convention was in possession of national prototype metres and kilograms that were calibrated against those in use elsewhere in the world. This led to the Mendenhall Order which redefined the customary units by referring to the national metric prototypes, but used the conversion factors of the 1866 act. In 1896 a bill that would make the metric system mandatory in the United States was presented to Congress. Of the 29 people who gave evidence before the congressional committee who were considering the bill, 23 were in favor of the bill, but six were against. Four of the six dissenters represented manufacturing interests and the other two the United States Revenue service. The grounds cited were the cost and inconvenience of the change-over. The bill was not enacted. Subsequent bills suffered a similar fate.
   During the nineteenth century the metric system of weights and measures proved a convenient political compromise during the unification processes in the Netherlands, Germany and Italy. In 1814, Portugal became the first country not part of the French Empire to officially adopt a metric system. Spain found it expedient in 1858 to follow the French example and within a decade Latin America had also adopted the metric system, or had already adopted the system, such as the case of Chile by 1848. There was considerable resistance to metrication in the United Kingdom and in the United States, though once the United Kingdom announced its metrication program in 1965, the Commonwealth followed suit.
   The Weights and Measures Act of 1878 effectively prohibited the use of metric weights for trade, the United Kingdom having declined to sign the Convention of the Metre three years previously. The standard imperial yard was not stable – in 1947 its rate of shrinkage was quantified and found to be one part per million every 23 years. In April 1884 HJ Chaney, Warden of Standards in London unofficially contacted the BIPM (custodians of the standard metre) inquiring whether the BIPM would calibrate some metre standards that had been manufactured in the United Kingdom. Broch, director of the BIPM replied that he was not authorised to perform any such calibrations for non-member states. On 17 September 1884, the British Government signed the convention on behalf of the United Kingdom. The Weights and Measures Act of 1897 authorized the use of metric units for trade; a list of metric to imperial equivalents being published the following year.
   Since then, the SI has officially been adopted by all countries except the United States, Liberia, and Myanmar. Both Myanmar and Liberia make substantial use of SI units, as do the scientific, military, and medical communities in the US. Countries such as the United Kingdom, Canada, and certain islands in the Caribbean have partially metricated, currently employing a mixture of SI, imperial, and US Customary units. For instance, road signs in the United Kingdom continue to use miles whilst produce in Canada and the United Kingdom continue to, in certain context, be advertised in pounds rather than kilograms. The incomplete processes of metrication in Canada and the United Kingdom illustrate the complex status of metrication internationally beyond the three countries (US, Myanmar, and Liberia) commonly cited as not having adopted the SI.
   The U.S. government passed the Metric Conversion Act of 1975, which made the metric system "the preferred system of weights and measures for U.S. trade and commerce". The legislation states that the federal government has a responsibility to assist industry as it "voluntarily" converts to the metric system, i.e., metrification. This is most evident in U.S. labeling requirements on food products, where SI units are almost always presented alongside customary units. According to the CIA Factbook, the United States is one of three nations (along with Liberia and Myanmar) that have not adopted the metric system as their official system of weights and measures.
   In 1889 sets of new international prototype metres and kilograms made from a 90% platinum, 10% iridium alloy were manufactured by the London firm Johnson Matthey and delivered to the CGPM who calibrated them against the 1799 prototype. One master copy and a set of working copies were retained by the BIPM and the rest distributed to member nations. At intervals of about 25 years each nation returned their copies for re-calibration against the master copies.
   The seminal 1875 Treaty of the Metre resulted in the fashioning and distribution of metre and kilogram artefacts, the standards of the future coherent system that became the SI, and the creation of an international body "Conférence générale des poids et mesures" or CGPM to oversee systems of weights and measures based on them.
   On July 4, 1876, Melvil Dewey (known for his Dewey Decimal Classification) incorporated the American Metric Bureau in Boston to sell rulers and other metric measuring tools. Dewey had hoped to make his fortune selling metric supplies.
  
  Section::::History.:20th century.
  
  The General Conference on Weights and Measures is the governing body for the modern metric system and comprises the signing nations of the Treaty of the Metre. The General Conference on Weights and Measures approved an updated version of the metric system in 1960 named "Le Système international d'unités" ("International System of Units") and abbreviated "SI".
   When colonies attained dominion status, they also attained the right to control their own systems of weights and measures. Many adopted the imperial system of units with local variations. India and Hong Kong supplemented the imperial system of units with their own indigenous units of measure, parts of Canada and South Africa included land survey units of measure from earlier colonial masters in their systems of measure while many territories used only a subset of the units used in the United Kingdom—in particular the stone, quarter and cental were not catalogued in, amongst others, Australian, Canadian and Indian legislation. Furthermore, Canada aligned her ton with US measures by cataloguing the ton of 2000 lb as being legal for trade, but kept the imperial gallon.
   As the industrial era dawned in Britain as well as continental Europe and overseas, the cgs system of units as adopted by the British Association for the Advancement of Science in 1873 with its plethora of electrical units continued to be the dominant system of measurement, and would remain so for at least the next 60 years. The advantages were several: it had a variegated set of derived units which, while not quite coherent, were at least homologous; the MKS system lacked a defined unit of electromagnetism at all; the MKS units were inconveniently large for the sciences; customary systems of measures held sway in the United States, Britain and the British empire, and even to some extent in France the birthplace of the metric system, which inhibited adoption of any competing system. Finally, war, nationalism and other political forces inhibited development of the science favouring a coherent system of units.
   Metrication in the United States
  
  Metrication (or metrification) is the process of introducing the International System of Units, also known as SI units or the metric system, to replace a jurisdiction's traditional measuring units. Although U.S. customary units have been defined in terms of metric units since the 19th century, as of 2019 the United States is one of only three countries (the others being Myanmar and Liberia) that have not officially adopted the metric system as the primary means of weights and measures.
   Section::::Adoption of metric weights and measures.:United States.
   Some members of Congress attempted to ban use of the metric system on federal highways in 1992 and 1993. These bills were not popular in the House of Representatives and failed before a vote.
  
  Section::::History.:20th century.:Mars orbiter blunder.
   BULLET::::- 1875 – Under the Convention of the metre, a new body the General Conference on Weights and Measures (CGPM) was set up and given responsibility for the new international prototype kilogram and international prototype metre which replaced the old French copies as the definitive prototype metre and kilogram.
  
  BULLET::::- 1881 – International Electric Congress agrees on standards for electrical units (formalised in 1893)
  
  BULLET::::- 1921 – Convention of the metre extended to cover all physical units of measure
   Although the new standard metre had the same value as the old metre, it had an "X" cross-section rather than a rectangular cross-section as this reduced the flexing when taking measurements. Moreover, the new bar, rather than being exactly one metre in length was a little longer than one metre and had lines engraved on them that were exactly one metre apart. The London firm Johnson Matthey delivered 30 prototype metres and 40 prototype kilograms. At the first meeting of the CGPM in 1889 bar No. 6 and cylinder No. X were chosen by lot as the international prototypes. The remainder were either kept as BIPM working copies or distributed by lot to member states as national prototypes.
   A series of conferences in France between 1870 and 1875 led to the signing of the Metre Convention and to the permanent establishment of the International Bureau of Weights and Measures, abbreviated BIPM after the French name. The BIPM made meter and kilogram standards for all the countries that signed the treaty; the two meters and two kilograms allocated to the United States arrived in 1890, and were adopted as national standards (Barbrow & Judson 1976, 16).
  
  Section::::Reasons for the change.
   Prior to 1960 the imperial and customary yard and the pound were sufficiently close to each other that for most practical purposes the differences in the sizes of units of length, area, volume and mass could be disregarded, though there were differences in usage - for example, in the United States short road distances are specified in feet while in the United Kingdom they are specified in yards The introduction of the international yard in 1960 caused small but noticeable effects in surveying in the United States which resulted in some states retaining the original definitions of the customary units of measure which are now known as the survey mile, foot, while other states adopted the international foot.
  
raw_presuppositions: US didn't want to use metric system.
raw_corrections: US tried to use metric system but nobody liked it. 