The United States House of Representatives is the lower house of the United States Congress, the Senate being the upper house. Together they compose the national legislature of the United States. The composition of the House is established by Article One of the United States Constitution. The House is composed of representatives who sit in congressional districts that are allocated to each of the 50 states on a basis of population as measured by the U.S. Census, with each district entitled to one representative. Since its inception in 1789, all representatives have been directly elected. The total number of voting representatives is fixed by law at 435. As of the 2010 Census, the largest delegation is that of California, with fifty-three representatives. Seven states have only one representative: Alaska, Delaware, Montana, North Dakota, South Dakota, Vermont, and Wyoming.