Every 10 years.
The U. S. Constitution requires that a census be taken during every ten-year period and that the results of the census be used to reapportion Representatives among the states according to their respective populations.
The USA. Constitution requires that each state have at least one representative in the lower house of Congress, the United States House of Representatives. See the Constitution of the United States, Article I, Section 2.
House of Representatives
The Constitution requires it.
The first way to amend the U.S. Constitution begins in Congress, where a proposed amendment must be approved by a two-thirds majority in both the House of Representatives and the Senate. Once Congress passes the amendment, it is sent to the states for ratification, where three-fourths of the state legislatures or conventions must approve it for the amendment to become part of the Constitution.
The Congressional Record. The Constitution requires Congress to keep a journal of its activities.
the house of representatives
it uses the congress to count the number of representatives
The Constitution requires that at least one half of the members of Congress be present in order to vote on a bill. Without that amount, a vote cannot be held.
On the contrary, the Constitution requires members of Congress to be residents of the States which they represent.
The United States Constitution requires that federal revenue bills be created by the House of Representatives. This is laid out in Article I, Section 7 of the Constitution.
The United States Constitution is based on the concept of popular sovereignty, which means rule by the people. The first three words of the Constitution---”We, the people”---imply popular sovereignty. Article 7 of the Constitution requires that nine states (the people of those states via the ballot box and representatives) approve (ratify) the new Constitution before it goes into effect. Article 5 of the Constitution provides for ways to amend the Constitution. Amendments are made through elected representatives of the people, another form of popular sovereignty. Article 1 creates the legislative branch and requires that representatives to Congress are elected by the people that are being represented. Thus, the concept of popular sovereignty is implied in all three Articles.