when did the us constitution go into effect

The U.S. Constitution went into effect on March 4, 1789. This date marks the beginning of the new government under the Constitution, after enough states had ratified it to establish a functioning framework for federal governance. The ratification process itself occurred when the ninth state (New Hampshire) ratified on June 21, 1788, which made the Constitution the law of the land, with the actual government transitioning when the first Congress convened and President Washington took office in March 1789.