"A resolution calling for a Constitutional amendment to accomplish nationwide Prohibition was introduced in Congress and passed by both houses in December 1917. By January 16, 1919, the Amendment had been ratified by 36 of the 48 states needed to assure it passage into law. Eventually, only two of those states—Connecticut and Rhode Island—opted out of ratifying it.[36][37] On October 28, 1919, Congress passed enabling legislation, known as the Volstead Act, to enforce the Eighteenth Amendment when it went into effect in 1920."

http://en.wikipedia.org/wiki/Prohibition_in_the_United_States

There was considerable desire among politicians of both parties to have the proposal made part of the Constitution before the 1920 general elections, so the President called a special session of the Congress so the proposal would be brought before the House again. On May 21, 1919, it passed the House, 42 votes more than necessary being obtained. On June 4, 1919, it was brought before the Senate and, after a long discussion, it was passed with 56 ayes and 25 nays. Within a few days, Illinois, Wisconsin, and Michigan ratified the amendment, their legislatures being in session. Other states followed suit at a regular pace, until the amendment had been ratified by 35 of the necessary 36 state legislatures. Much of the opposition to the amendment came from Southern Democrats, a trend which remained consistent with Tennessee as the last state to pass the amendment, during a special session right before the ratification period was to expire.[19] On August 18, 1920, Tennessee narrowly approved the Nineteenth Amendment, with 50 of 99 members of the Tennessee House of Representatives voting yes.[20] This provided the final ratification necessary to add the amendment to the Constitution.[21]

http://en.wikipedia.org/wiki/Nineteenth_Amendment_to_the_United_States_Constitution