The way this question is worded, there can be several possible answers. I will summarize a few possible answers.
The United States Congress is influenced by the shifts in our population. As our population moves from one region of the country to another region of the country, there has been a shift in the number of representatives in the House of Representatives from regions that are growing. States that are located in the Sun Belt, the South and West, are gaining more seats in the House of Representatives than states that are located in the Rust Belt, the North and East. People in these regions want different policies to occur. Thus, a shifting population may mean shifting policies taking place in our country.
The United States Congress is also influenced by our changing demographics. As Hispanic and African American population grow, more Hispanics and African Americans are being elected to Congress. The voices of these groups are also being heard more often and more clearly as they meet with and/or contact their elected representatives.
The United States Congress is also influenced by how districts are created to determine representation in the House of Representatives. When district lines are drawn so that a candidate from a given party is practically guaranteed to win a seat in the House of Representatives, these representatives don’t need to compromise on issues. They know as long as they support what the vast majority of people in their district support, they will get reelected. We have seen this happen in Congress today. There is less and less compromising because more and more seats in the House of Representatives are guaranteed to go to a certain political party because of how the boundary lines for that district are drawn.
Some people would say the United States Congress is greatly influenced by special interest groups and money. These groups are well funded, and they can spend a lot of money supporting or attacking a candidate or a particular issue facing the country. These groups may be able to convince elected officials to vote a certain way by promoting, accurately or inaccurately, one side of a particular issue.
Congress is influenced by many different factors today.