May 7, 1992 – Michigan ratifies a 203-year-old proposed amendment to the United States Constitution making the 27th Amendment law. This amendment bars the U.S. Congress from giving itself a mid-term pay raise.

The Twenty-seventh Amendment (Amendment XXVII) to the United States Constitution prohibits any law that increases or decreases the salary of members of Congress from taking effect until the start of representatives' next set of terms of office. It is the most recently adopted amendment but was one of the first proposed.

The 1st Congress submitted the amendment to the states for ratification on September 25, 1789, along with 11 other proposed amendments (Articles I–XII). The last ten Articles were ratified in 1791 to become the Bill of Rights, but the first two, the Twenty-seventh Amendment and the proposed Congressional Apportionment Amendment, were not ratified by enough states to come into force with them.

​The proposed congressional pay amendment was largely forgotten until 1982, when Gregory Watson, a 19-year-old sophomore at the University of Texas at Austin, wrote a paper for a government class in which he claimed that the amendment could still be ratified. An unconvinced teaching assistant graded the paper poorly, motivating Watson to launch a nationwide campaign to complete its ratification.

Initially, the process was slow, but as more states voted to ratify, the movement gained national attention leading to apparently Michigan being the 39th state to ratify on May 7, 1992.  Although the amendment was subsequently certified on May  19, 1992 and published in the Congressional Record with both housing of Congress voting the following day to accept the amendment as ratified by the requisite 2/3's majority of the states, it was subsequently discovered that Kentucky, which was initially recorded as not having ratified the amendment until March 21, 1996, had actually ratified on June 27, 1792 following admission to the Union.  Thus, the 27th Amendment was legally ratified on May 5, 1992, when Missouri and Alabama had both ratified.  

Image: Gregory Watson in 2017.  Watson originally received a C- on his paper, which was subsequently changed to an A in 2017 in recognition of his achievement in having the Amendment ratified.