Third Flag Act
After the War of 1812 it was obvious that the Flag Law of 1795 would have to be amended. Since the admittance of the fifteenth state, Kentucky, three more states had been admitted: Tennessee (June 1, 1796), Ohio (March 1, 1803), and Louisiana (April 30,1812). Indiana followed (December 11, 1816), as did Mississippi (December 10, 1817). That meant there were then five states that were not represented on the nation's flag.
In 1816, Congressman Peter Wendover (NY) convinced Congress that action was necessary and he was made chairman of a committee to study the problem. Wendover sought the advice of Samuel Reid, a naval hero of the War of 1812. Reid suggested reducing the number of stripes to 13 to symbolize the original colonies, and using one additional star for each state admitted into the Union thereafter. On March 25, 1818 the Third Flag Act was passed. It was signed into law on April 4, 1818.
On April 13, 1818 a version of the flag representing the Third Flag Act was raised over the Capitol dome. Sewn by Samuel Reid's wife, it contained 13 red and white horizontal stripes and 20 white stars forming one larger star in the canton of blue (shown above).
Later in 1818, President James Monroe ordered that the stars be in four equal, parallel rows of five each. This flag then replaced that sewn by Mrs. Reid but lasted only one year, as Illinois became the 21st state on December 3, 1818.