Each Representative in the United States House is elected from a geographically defined district they represent, and there are 435 total voting Representatives in the United States House. The number of Representatives per state is based up on the state's population.
The number of representatives with full voting rights is 435, established by law August 8, 1911. The 435 congressional seats are apportioned to the states based upon decennial census population numbers. The states are then responsible for defining the districts within their states from which the people in those districts a Representative. The states are to make each such district as equal in population as the other districts in the state as is practical. The state legislatures establish the boundaries of the districts and sometimes court orders are required as well.
The United States Constitution established minimum and maximum sizes for the United States House. The Constitution also requires that a Representative must be at least 25 years old and must be a citizen of the United States for no less than seven years. The Representative also must be an inhabitant of the state he or she represents. Not included in the 435 are some non-voting Representatives from the United States territories, such as Guam and the Virgin Islands.