A number of States were admitted to the Union while Monroe was President. The first was Mississippi, in 1817. The territory was claimed by Georgia, which gave it to the United States in 1802. Illinois was admitted in 1818, being the third of the five States formed from the old Northwest Territory. Alabama became a State in 1819, and had been a part of the territory claimed by Georgia. Maine was admitted in 1820, and, as has been shown, was for a long time a part of Massachusetts, and Missouri became a State in 1821. The strife over the admission of the last-named State was so angry that more than one person saw the shadow of the tremendous civil war that was to darken the country and deluge it in blood forty years later. The invention of the cotton gin in 1793 had made cotton the leading industry of the South and given an enormous importance to slavery. The soil and the climate and economic conditions caused it to flourish in the South, and the lack of such conditions made it languish and die out in the North. Missouri applied for admission in March, 1818, but it was so late in the session that Congress took no action. At the following session a bill was introduced containing a provision that forbade slavery in the proposed new State. The debate was bitter and prolonged, accompanied by threats of disunion, but a compromise was reached on the 28th of February, 1821, when the agreement was made that slavery was to be permitted in Missouri, but forever prohibited in all other parts of the Union, north and west of the northern limits of Arkansas, 36 deg. 30', which is the southern boundary of Missouri. The State was admitted August 21st, increasing the number to twenty-four. The census showed that in 1820 the population of the United States was 9,633,822. The State of New York contained the most people (1,372,111); Virginia next (1,065,116); and Pennsylvania almost as many (1,047,507). PRESIDENTIAL ELECTION OF 1820. It was in the autumn of 1820, during the excitement over the admission of Missouri, that the presidential election occurred. The result is not likely ever to be repeated in the history of our country. There was no candidate against Monroe, who would have received every electoral vote, but for the action of one member, who declared that no man had the right to share that honor with Washington. He therefore cast his single vote for Adams of Massachusetts. For Vice-President, Daniel D. Tompkins, Republican, received 218; Richard Stockton, of New Jersey, 8; Daniel Rodney, of Delaware, 4; Robert G. Harper, of Maryland, and Richard Rush, of Pennsylvania, 1 vote each. Monroe and Tompkins were therefore re-elected. THE MONROE DOCTRINE.