The United States of America is a federal republic consisting of 50 states, a federal district, five major territories, and minor islands. Both the states and the United States as a whole are each sovereign jurisdictions. The Tenth Amendment to the United States Constitution allows states to exercise all powers of government not delegated to the federal government. Each state has its own constitution and government. All states and their residents are represented in the federal Congress, a bicameral legislature consisting of the Senate and the House of Representatives. Each state elects two senators, while representatives are distributed among the states in proportion to the most recent constitutionally mandated decennial census.