On April 5, 1792, George Washington cast the first Presidential veto. From the article:
"George Washington exercises first presidential veto
George Washington exercises the first presidential veto of a Congressional bill on April 5, 1792. The bill introduced a new plan for dividing seats in the House of Representatives that would have increased the amount of seats for northern states. After consulting with his politically divided and contentious cabinet, Washington, who came from the southern state of Virginia, ultimately decided that the plan was unconstitutional because, in providing for additional representatives for some states, it would have introduced a number of representatives higher than that proscribed by the Constitution.
After a discussion with the president, Thomas Jefferson wrote in a letter that votes for or against the bill were divided along perfectly geographical lines between the North and South. Jefferson observed that Washington feared that a veto would incorrectly portray him as biased toward the South.
In the end, Jefferson was able to convince the president to veto the bill on the grounds that it was unconstitutional and introduced principles that were liable to be abused in the future. Jefferson suggested apportionment instead be derived from arithmetical operation, about which no two men can ever possibly differ.” Washington’s veto sent the bill back to Congress. Though representatives could have attempted to overrule the veto with a two-thirds vote, Congress instead threw out the original bill and instituted a new one that apportioned representatives at “the ratio of one for every thirty-three thousand persons in the respective States.”
Washington exercised his veto power only one other time during his two terms in office. In February 1797, the former commanding general of the Continental Army vetoed an act that would have reduced the number of cavalry units in the army."