Under the U.S. Constitution the president and vice president are chosen by electors, under a constitutional grant of authority delegated to the legislatures of the several states. The Constitution reserves the choice of the precise manner for selecting electors to the will of the state legislatures. It does not define or delimit what process a state legislature may use to create its "state" college of electors. In practice, the state legislatures have generally chosen to select electors through an indirect popular vote, since the 1820s. Most states use a "winner-take-all" system in which all the state's electors are awarded to the candidate gaining the most popular votes. Maine and Nebraska allow individual congressional districts to elect one elector.