The United States of America have a Bicameral Congress. Their lawmaking body consists of two chambers which are the Senate and the House of representatives.
Senate represents the legislative aspect of the country such as political subdivisions whilst the House of Representatives stands for the individual citizens of the country.
The United States chose to have a Bicameral Congress as for one, it provides an effective system of balancing the enactment of laws made, so that it will not be unfair to certain groups within the state. Two, having two minds contemplating and brainstorming on creating a law is better than having to do it with one body.