Did you know that the US House of Representatives has a fixed number of seats (435)? It wasn’t always that way. The number of seats used to vary based on the size of the population, which was measured every 10 years in via the census.

I recently learned that a law was passed back in 1929 that capped the number of seats at 435.

I searched but could not find a chart showing the number of seats over time, so I tediously went through the records of all congresses since the US was founded (there’s been 118 as of this writing, thanks Wikipedia) and plotted the number of house seats. Above is the chart that I came up with. Do you see how it generally rises in steps? Those steps represent the US census that’s taken every 10 years. The only weird period in the data was between congresses 35 and 41, during the civil war, but the rest is pretty consistent, up until the flatline that began at the 62nd congress.

Why was the size of the house capped? Because the 1920 census revealed a shift as large numbers of people moved from rural farms into cities, and rural voters wanted to maintain power. Quite the power grab, eh?