The size or representation in the U.S. House of Representatives is determined by Congress. It has the power to control the size of House. The size has been mixed and varied over the years. This in turn is reflected by the admission of new states, reappointment after a census has been conducted or historically, the Civil War. Representatives are also determined according to population. There are 435 members of the U.S. House of Representatives. These are further divided among the 50 states.
For more information on the U.S. House of Representatives visit: http://www.house.gov/