article

The road towards metrication in the United States has been rocky and unsteady. In some fields, the metric system has been used in the United States since the early 1800s. The United States has been gradually increasing its use of metric units for many years, but much of the public momentum has been lost since the 1980s, except in schools, science, and manufacturing.

19th century

In the early 1800s, the U.S. Coast and Geodetic Survey (the government's surveying and map-making agency) used meter and kilogram standards brought from France. In 1866, Congress authorized the use of the metric system and supplied each state with a set of standard metric weights and measures.

In 1875, the United States solidified their commitment to the development of the internationally recognized metric system by becoming one of the original seventeen signatory nations to the Convention du Mètre. The signing of this international agreement concluded five years of meetings in which the metric system was reformulated, refining the accuracy of its standards. The Treaty of the Meter, also known as the "Meter Convention", established the Bureau international des poids et mesures (BIPM, International Bureau of Weights and Measures) in Sèvres, France, to provide standards of measurement for worldwide use.

In 1893, under the Mendenhall Order, metric standards, developed through international cooperation under the auspices of BIPM, were adopted as the fundamental standards for length and mass in the United States. The customary measurements – the foot, pound, quart, etc. – have been defined in relation to the meter and the kilogram ever since.

The 1895 Utah Constitution mandates in Article 10, Section 11, that "The Metric System shall be taught in the public schools of the State".

20th century

The Conférence Générale des Poids et Mesures (General Conference on Weights and Measures), the governing body that has overall responsibility for the metric system, and which is made up of the signatory nations to the Treaty of the Meter, approved an updated version of the metric system in 1960. This modern system is called Le Système International d'Unités or the International System of Units, abbreviated SI.

On February 10, 1964, the National Bureau of Standards (now known as the National Institute of Standards and Technology) issued the following statement:

Henceforth it shall be the policy of the National Bureau of Standards to use the units of the International System (SI), as adopted by the 11th General Conference of Weights and Measures (October 1960), except when the use of these units would obviously impair communication or reduce the usefulness of a report.

The United Kingdom began a transition to the metric system in 1965 to more fully mesh its business and trade practices with those of the European Economic Community. The conversion of the United Kingdom and the Commonwealth nations to SI created a new sense of urgency regarding the use of metric units in the United States.

In 1968, Congress authorized a three-year study of systems of measurement in the U.S., with particular emphasis on the feasibility of adopting SI. The detailed U.S. Metric Study was conducted by the Department of Commerce. A 45-member advisory panel consulted with and took testimony from hundreds of consumers, business organizations, labor groups, manufacturers, and state and local officials.

The final report of the study, "A Metric America: A Decision Whose Time Has Come," concluded that the U.S. would eventually join the rest of the world in the use of the metric system of measurement. The study found that measurement in the United States was already based on metric units in many areas and that it was becoming more so every day. The majority of study participants believed that conversion to the metric system was in the best interests of the nation, particularly in view of the importance of foreign trade and the increasing influence of technology in American life.

The study recommended that the United States implement a carefully planned transition to predominant use of the metric system over a ten-year period. Congress passed the Metric Conversion Act of 1975 "to coordinate and plan the increasing use of the metric system in the United States." The Act, however, did not require a ten-year conversion period. A process of voluntary conversion was initiated, and the U.S. Metric Board was established. The Board was charged with "devising and carrying out a broad program of planning, coordination, and public education, consistent with other national policy and interests, with the aim of implementing the policy set forth in this Act." The efforts of the Metric Board were largely ignored by the American public, and in 1981, the Board reported to Congress that it lacked the clear Congressional mandate necessary to bring about national conversion. Due to this apparent ineffectiveness, and in a Reagan effort to reduce federal spending, the Metric Board was disestablished in the fall of 1982.

The Board's demise increased doubts about the United States' commitment to metrication. Public and private sector metric transition slowed at the same time that the very reasons for it became more pressing: the increasing competitiveness of other nations and the demands of global marketplaces.

Congress included new encouragement for U.S. industrial metrication in the Omnibus Trade and Competitiveness Act of 1988. This legislation amended the Metric Conversion Act of 1975 and designates the metric system as "the Preferred system of weights and measures for United States trade and commerce". The legislation states that the Federal Government has a responsibility to assist industry, especially small business, as it voluntarily converts to the metric system of measurement.

Federal agencies were required by this legislation, with certain exceptions, to use the metric system in their procurement, grants and other business-related activities by the end of 1992. While not mandating metric use in the private sector, the Federal Government has sought to serve as a catalyst in the metric conversion of the country's trade, industry, and commerce. Exceptions were allowed for the highway and construction industries. The Department of Transportation was planning to require metric units by 2000, but this plan was canceled by the 1998 highway bill TEA21. * Use in the U.S. military is generally high, due, in part, to the need to interchange ammunition and parts with other nations' militaries. (The US continues to use fractions of an inch for caliber on some older guns.)

Some members of Congress attempted to ban use of the metric system on federal highways in 1992 and 1993. *

21st century

Pro-metrication efforts

The current effort toward national metrication is based on the claim that industrial and commercial productivity, mathematics and science education, and the competitiveness of American products and services in world markets would be enhanced by completing the change to the international standard measurement system based on metric units. Many or most Americans, however, remain unconvinced of this position, or disagree over whether and how to pay and enforce complete conversion, which, if undertaken, could possibly incur considerable expense in the near term for millions of businesses and government agencies.

A potential problem for current metrication efforts is that many or most Americans, thirty years after the 1970s metric push, have little interest in metric usage. Daily life no longer features even dual usage of units such as Celsius for temperature, so most Americans have little contact with metric units on a daily basis. Those who need to use the metric system for work learn it, those who travel overseas learn enough to get by, but most others do not feel generally compelled to use it.

The use of two different systems was the contributing factor in the loss of the Mars Climate Orbiter in 1998. NASA specified metric units in the contract. NASA and other organizations worked in metric units but one subcontractor, Lockheed Martin, provided thruster performance data to the team in pound force seconds instead of newton seconds. The spacecraft was intended to orbit Mars at about 150 km altitude, but the incorrect data meant that it probably descended instead to about 57 km, burning up in the Martian atmosphere.

Current usage

Daily life
While most Americans have heard of the metric system, metric usage remains low at the individual level. Weather reports on television are given in customary units (with the exception of hurricanes, where pressure is typically given in millibars at the national level). Few Americans understand the Celsius temperature scale, and would not know what to wear if outside temperature were reported to be 12° Celsius. The BTU remains the common measure of heating and cooling. Clothing is measured in inches or sizes. The more common SI prefixes are widely known, but not necessarily in connection with the metric system. For example, computer speeds are measured in gigahertz and a lottery is named Megabucks. The letter K is widely accepted as meaning "thousand" (e.g., "She earned over 100K last year"). This usage has largely replaced the abbreviation m that was commonly used for "thousand" before the 1960s.

Consumer and retail
Most products are sold in English quantities, with a metric equivalent shown, e.g. "1 lb (454 g)". Some items are produced and sold in rounded metric quantities (e.g., dental floss is often sold in 50 meter packages). Perhaps the most common metric item sold is the 2-liter bottle of soft drinks. Some supermarket chains also make their store brand soft drinks available in 3-liter party sizes as well. Half-liter (500 ml) and one-liter containers of soft drinks are increasingly sold alongside more traditional 12 oz, 16 oz, 20 oz, and 24 oz (710 ml) sizes

However, attempts to sell 3- or 4-liter bottles of milk, instead of gallons, have been largely unsuccessful. Wine is sold in standard bottles of 750 ml, following the practice of the rest of the world, and a fifth of liquor, once one fifth of a gallon or 757 ml, is now commonly 750 ml. Bottled water is commonly found in half-liter and one-liter sizes, but 20 and 24 oz sizes remain common.

Household products such as shampoo, mouthwash, and dental floss have begun to be sold in metric sizes, and PowerBars and similar products have always been sold (but not marketed) by the gram. Consumer-size photographic film is commonly sold in a 35 mm standard, although print sizes and large format films are defined in inches. The standard method for sizing tires combines millimeters for tread width and inches for rim diameter.

Since 1992, the federal Fair Packaging and Labeling Act (FPLA) has required consumer goods to be labeled in both customary and metric units. There is a strong effort underway by industry to amend this law to allow manufacturers to use metric-only labeling. Most states in the U.S. have already adopted laws allowing metric-only labeling. *. This directive was originally to be implemented on 1 January 1990 and two 10-year extensions have subsequently been granted, extending the deadline to 2010. It is questionable as to whether a third extension would be granted. Pending the EU deadline, an amendment to the FPLA to allow metric-only labeling would allow manufacturers, both importers and exporters, to avoid the significant costs associated with having to produce two distinct package types. A significant advance in American metrication could result from some products displaying metric weights and measures only.

Construction
The construction industry has been the slowest to adopt metric units. Dimensional lumber still comes in standard inch widths and depths (e.g., "2 by 4's"), although the finished, cured lumber will not actually have the indicated dimensions. Lengths are commonly 8 and 16 feet. Building codes are established at the local level and the U.S. has extensive building standards that are based on English units. Because of Canada's proximity to the U.S., issues of common units still arise. (Even in other otherwise metricated countries, units customary for that country often continue to be used; for example, traditional construction in Japan still uses Japanese units predating metrication.)

Education
Most students are taught the metric system in elementary school. Instruction primarily centers on the concepts of powers of 10, the associated prefixes, and the conversion from one prefix form to another. Units of length, volume, and mass are also typically introduced through comparison with ordinary objects. The lack of popular metric usage, however, provides little reinforcement. As a result, while students might understand some of the concepts underlying the metric system, they do not necessarily have an intuitive sense of what the units mean. Furthermore, the fundamental concept that all metric units are derived from a few base units is rarely taught outside of physics and some chemistry classes.

Electricity and energy
There are no customary U.S. units for electric current, potential difference, charge etc. The metric ones (ampere, volt, coulomb, etc.) have always been used. Energy is often measured in watt-hours, rather than the SI joule, and also in BTUs. The rated power of motors and even power plant steam turbines is frequently quoted in horsepower.

Heating, cooling and combustion power are often measured in BTUs per hour. Fuel prices are mostly given in customary units, e.g. dollars per gallon, per barrel, per thousand cubic feet, per long ton, etc. The SI term hertz has completely replaced the older term cycles per second as a unit of frequency.

Financial services
The United States was one of the first nations to introduce decimalized currency. Some commodity market prices are quoted in customary units (e.g., barrels of oil, troy ounces of gold, etc.); others are quoted in metric units (e.g., metric tons (tonnes) of wheat).

Manufacturing
Globalization of manufacturing has led to wide adoption of metric standards, although this is not yet universal. After a confusing period where automobiles were assembled with both customary and metric fasteners in each vehicle, cars are now universally built with metric parts. Automobile engines, formerly having been measured in cubic inches, are currently measured in liters.

The electronics and computer industries largely converted to metric standards as new technologies were introduced toward the end of the 20th century. Thus 5-1/4 inch floppy disks were truly in 5-1/4 inch-wide packages. They were replaced by "3-1/2 inch" disks that were actually 90 mm wide. CD/DVD disks are 120 mm in diameter, but their size is rarely mentioned.

Military
The U.S. military uses metric measurements extensively to ensure interoperability with allied forces (particularly NATO STANAGs, "standardization agreements"): measuring distances in "klicks" (slang for kilometers), and using millimeter-sized ammunition, though a few legacy exceptions exist, e.g. .50-caliber guns. Most military vehicles are built to metric standards. An exception is the U.S. Navy whose undersea fleet measures distances in terms of "kiloyards," depth as "feet", and velocity, in some cases, as "feet per second" and "knots."

Science and medicine
In science, metric usage is essentially universal, consistent with worldwide usage, although additional specialized units are often utilized for specific purposes in various disciplines (such as the light-year in astronomy). Medicine is generally metric, but where interaction with patients is required, usage is often mixed. Doctors often measure a patient's weight in pounds to compute a dosage of medicine administered in grams or milliliters. Even in many cases for which metric units are otherwise used, U.S. practice often varies from the rest of the world. For example, U.S. diabetes patients measure their blood sugar levels in milligrams per deciliter, whereas most other countries use millimoles per liter.

In hospital settings, patient data is typically recorded using metric quantities, but all interaction with patients is done with reference to customary units (i.e., patient weights might be recorded in kilograms but discussed with patients in pounds).

Usage among veterinarians varies, but due to the heavy emphasis on public interaction, animal weights (e.g., for cats or dogs) is nearly always recorded and reported in pounds and ounces.

Sports
Americans are frequently exposed to metric units through coverage of international sporting events, particularly the Olympic Games. Races in the U.S. are run in metric distances (e.g., the 100 meter sprint and 5 km ("5K") races). Measured distances as used in events such as shot put, high jump, and discus throw are, however, often in feet and inches, except at the international level. Even most casual runners prefer to think of a "10K" race as a "6.2 mile" race. The field and court sizes for most popular team sports (even soccer) were originally set in English units. Some sporting equipment, such as skis and poles, is sold in metric units. Bicycles, especially at the high end, are increasingly being sold and sized in metric (for example, a frame described as "21 inch" size in the past is now often labeled as a "53 cm" frame instead).

Transportation
Highway speed limits are posted in miles per hour and distances are largely announced in miles, yards, or feet, although a few dual mile/km signs can be found, mostly left over from demonstration projects that are no longer supported. * One exception is Interstate 19 in Arizona, which is almost completely signed in metric, except for speed limit signs. Signage on this road is, however, being converted to back to traditional units as they are replaced.

Since 2000, the Manual on Uniform Traffic Control Devices has been published in both metric and American Customary Units. Metric signs, including speed signs in kilometers per hour, are now displayed in the manual even though they are not practically used on the roads. This part of the metrication is ahead of the United Kingdom. *

Due to their proximity to Canada, the states of New Hampshire and Maine include distances in both miles and kilometers on highway signs, although some older signs still have miles only. However, exits in Maine are numbered according to the number of miles from the southern or western terminus of the route. At least one route (US 31) in Alabama has both mileposts and kilometer-posts.

Gasoline and diesel fuel are both sold by the gallon, and fuel economy is rated in miles per gallon. Domestic airline flights are assigned altitudes in feet and measure speed in knots. Nautical charts show depth in fathoms and use the nautical mile for distance (one minute of arc at the radius of the earth at sea level is one nautical mile). Railroads use the standard gauge of 4 feet 8-1/2 inches, as does most of Europe (where it is expressed instead as 1435 mm). Speedometers on automobiles designed to American specifications contain both miles-per-hour (MPH) and kilometers-per-hour (km/h), but the odometers are in miles only. (Unlike most other American vehicles, Cadillac has cars with speedometers with miles per hour only.)

Popular culture

The Simpsons

  • In A Star is Burns Grampa Simpson angrily denounces Marge Simpson's plan to switch to the metric system, yelling "The metric system is the tool of the devil! My car gets forty rods to the hogshead, and that's the way I likes it!" (That translates into 432 (beer) or 504 (wine) gallons per mile, or about 1.2 liters per meter.)
  • In another, entitled Homer the Great, Homer joins a secret society called the Stonecutters. The members sing a drinking song, proudly boasting: "Who controls the British Crown? Who keeps the metric system down? We do! We do!"
  • In the episode Homer and Apu Homer shows he understands the metric system better than the customary one. After he announces his plans to go to India, Lisa informs him it is "over 10,000 miles away". He responds appearing to understand her. She then states that that is "over 16,000 kilometers" to which he replies "D'oh".
  • In another episode, Judge Constance Harm orders Bart to remain at least 25 feet away from Lisa as part of a restraining order. Judge Harm then says it is seven and a half meters, prompting French, German, and Swiss spectators to be shocked.
  • In the episode They Saved Lisa's Brain, Lisa joins Mensa, which, as a "council of learned citizens", takes over rule in Springfield after the mayor skips town. The Council proceeds to reform daily life in Springfield, to include timetables for trains. In the words of Principal Skinner, "Not only are the trains running on time, they are running on metric time. Remember this time people, 80 past 2 on April 47th, it's the dawn of an enlightened Springfield."
  • In the episode The Seven-Beer Snitch, it is revealed that Springfield was first city in America to abandon the metric system.

Star Trek

  • During the first season of The Original Series, all characters commonly used customary units despite multiple Earth national origins and the show's setting in the 23rd century. Later, starting with "The Changeling", metric measures were used, although sometimes the writers lapsed back into customary. In the movies, The Next Generation and subsequent series (including Enterprise, which is set a century before the original series), metric was used exclusively. Sometimes writers chose metric units not from the SI, but from the CGS systems, like megadynes, which are deprecated already.

Futurama

  • Futurama is a satirical cartoon set in the future. As in the original Star Trek, both metric and standard units appear.
  • In the episode The Series Has Landed, a lunar farmer informs Fry, the main character, of the temperature drop during a lunar night:
Farmer: "Drops down to minus 173."
Fry: "Fahrenheit or celsius?"
Farmer: "First one, then the other."

Saturday Night Live

  • In an episode of Saturday Night Live, Dan Aykroyd appears as a United States government official explaining the forthcoming metric alphabet, or "Decibet," wherein the first four letters are unchanged; "E F," "G H I," and "L M N O" are each combined into single letters; and the remaining "trash letters" are combined into an unintelligible blotch. He then proceeds with a comic explanation of how this will affect spelling and pronunciation.

Hybrid Units

Some measurements are done in units derived from both customary and metric units. For example:
  • Power per unit length from a nuclear reactor fuel rod: kilowatts per foot
  • Heat rate from a power plant: BTUs per hour per kilowatt
  • Distance to target for a U.S. submarine: kiloyards.

External links

Economic history of the United States | Metrication

 

This article is licensed under the GNU Free Documentation License. It uses material from the "Metrication in the United States".

Home Page • arts • business • computers • games • health • hospitals • home • kids & teens • news • physicians • recreation• reference • regional • science • shopping • society • sports • world