How "democratic" is Congress?

Article I of the Constitution grants all legislative powers of the federal government to a Congress divided into two chambers, a Senate and a House of Representatives. The Senate is composed of two members from each state as provided by the Constitution. Its current membership is 100. Membership in the House is based on each state's population, and its size is therefore not specified in the Constitution. Its current membership is 435. This bicameral structure is designed to balance the interests of both large and small states.

The Seventeenth Amendment, adopted in 1913, provided for direct election of the Senate. Members are elected by the people of their respective districts or states, with the House of Representatives members serving two-year terms and the Senators serving six-year terms. This process ensures that the members of Congress are accountable to their constituents and that the government is representative of the people.

Balance of power

While there was intense debate in the convention over the makeup and powers of Congress, many delegates believed that the legislative branch would be relatively unimportant. A few believed that the Congress would concern itself largely with external affairs, leaving domestic matters to state and local governments. These views were clearly mistaken. The Congress has proved to be exceedingly active, with broad powers and authority in all matters of national concern. While its strength vis-à-vis the executive branch has waxed and waned at different periods of American history, the Congress has never been a rubber stamp for presidential decisions.

If we sort the states from largest to smallest in terms of population and then graph them with (cumulative) number of senators on the horizontal axis and (cumulative) population on the vertical axis, we see how unevenly the population is distributed among senate "districts" (i.e., states). Non-state territories like Puerto Rico and the District of Columbia have no senators.

The 9 largest states account for 50% of the country's population. Half of the Senate represents about 83% of the population, while the other half represents another 16%. 1% has no representation whatsoever in the Senate.

The House of Representatives is designed to be more equally representative, following the idea of "one person, one vote". If we sort the House's 435 districts by population and graph them in the same way, the result is much closer to a straight diagonal line:

Representation in the House of Representatives

There are still little jumps. There's a big one at the beginning: Puerto Rico is the size of about 4 average-sized districts but has no voting representatives. Around representative #417, there's another little jump because the District of Columbia has more people than almost 20 districts, but also has no voting representatives.

With 435 districts, it's hard to see from that graph that there's real variation in the population of each district. The number of representatives hasn't changed since 1929, and districts can't cross state borders, so some states end up with more or fewer districts - and each district with more or fewer residents - than if each district had the same number of people.

If all districts had the same number of people, they would each have about 770,500 people. But in reality, some districts, like Montana's at-large district, have many more people, which means less voting power per person. Others have many fewer residents than the average district, but they still get one representative in the House.

The data for the House of Representatives comes from the 116th Congress (2019-2021), which were in effect before the redistricting that followed the 2020 census. Once the new district data is available from the American Community Survey, we can recreate these graphs for the districts that will take effect in January 2023.

This analysis was inspired by "American Democracy Was Never Designed to Be Democratic", by Louis Menand in The New Yorker.