The National Prohibition Act (18th Amendment) was ratified on January 16th, 1919 with North Carolina, Utah, Nebraska, Missouri and Wyoming all approving the amendment on January 16, 1919 giving the required 36 states (Delaware was the 9th) to approve the amendment. This gave everyone one year to stock up on alcohol before the amendment went into effect. It is frequently thought that having possession of alcohol was against the law but the amendment merely deny manufacture, sale and transportation of liquors and on January 17, 1920 it went into effect.
Section 1. After one year from the ratification of this article the manufacture, sale, or transportation of intoxicating liquors within, the importation thereof into, or the exportation thereof from the United States and all territory subject to the jurisdiction thereof for beverage purposes is hereby prohibited.
Section 2. The Congress and the several states shall have concurrent power to enforce this article by appropriate legislation.
Section 3. This article shall be inoperative unless it shall have been ratified as an amendment to the Constitution by the legislatures of the several states, as provided in the Constitution, within seven years from the date of the submission hereof to the states by the Congress.