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Metric events and anniversaries

Shown below are some metric-system-related events and anniversaries.

Those highlighted in yellow are sponsored by various organizations and are generally observed each year, while the others are not formally observed but are anniversaries that might be of interest.


1st week — Weights and Measures Week — The National Conference on Weights and Measures (NCWM) sponsors a national Weights and Measures Week during the first full week of March, to celebrate “the trust that is built into every transaction by a national, local and state weights and measures system.”


5 — Mendenhall Order — On 5 April 1893, the Mendenhall Order was issued, declaring the meter and kilogram to be the fundamental standards of length and mass in the U.S. and defining the inch-pound units in terms of the metric system.


20 — World Metrology Day — On 20 May 1875, the Convention du Mètre, also known as the Metric Convention, Metrical Convention, Metre Convention, Convention of the Metre, or Treaty of the Meter, was signed by 17 countries, including the U.S. To recognize its anniversary, 20 May is World Metrology Day.


28 — Metric Act of 1866 — On 28 July 1866 the Metric Act of 1866, which legally recognized the metric system of measurement in the U.S., was enacted.


10 (week of) — National Metric Week — The week of October 10, i.e., 10/10, is declared to be National Metric Week, sponsored by the National Council of Teachers of Mathematics (NCTM) and the USMA.

14 — World Standards Day — The International Organization for Standardization (ISO) held its first meeting on 14 October 1946. “Each year on 14 October, the members of IEC, ISO and ITU celebrate World Standards Day, which is a means of paying tribute to the collaborative efforts of the thousands of experts worldwide who develop the voluntary technical agreements that are published as international standards.” Here's the Standards Engineering Society page about World Standards Day as well as NIST's page about World Standards Day 2010 and ANSI's page about World Standards Day 2010.

23 — Mole Day — An unofficial holiday to celebrate Avogadro's number, 6.02×10²³, the number of entities in a mole of a substance. “Mole Day” was originally suggested by an early 1980's article in The Science Teacher; for more information see the National Mole Day Foundation and read Wikipedia's article about Mole Day.


23 — Metric Conversion Act of 1975 — On 23 December 1975 the Metric Conversion Act of 1975 was enacted. Among other things, it designated the metric system as the preferred system of weights and measures for the U.S.

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Updated: 2010-11-09