The two parts of the Congressional Legislative Branch are the Senate and the House of Representatives. This branch was established by Article I of the United States Constitution.
The Senate consists of 100 senators, two for each state. Originally, senators were chosen by state legislators. After the ratification of the 17th Amendment, senators began being chosen by popular vote. They are elected to 6-year terms.
The House of Representatives consists of 435 elected members who are divided among the 50 states based on each state's total population. An additional six nonvoting members represent the District of Columbia, the Commonwealth of Puerto Rico and four other United States territories.