A U.S. congressman serves a term of two years, and the people of his district can re-elect him as many times as they wish, according to Article 1 of the U.S. Constitution. When the Founding Fathers wrote that document, they did not include term limits for any federal offices.
Many states, such as Arizona, California and Montana, have term limits for their state legislative bodies, and many U.S. congressmen follow self-imposed term limits.
The longest-serving U.S. congressman was John Dingell, who served for more than 59 years. The average length of service in the U.S. House of Representatives is 9.1 years.