Why hasn't the House of Representatives grown along with the population?

After the 1840 census — and in one of the last decades before the 14th Amendment ended the census's counting of an enslaved person as "three fifths'' of a free person — Congress did drop the number of House seats from 242 to 232. The latest census numbers showed an increase compared with the 1830 results, but Congress could only agree on a smaller House size after Senate pushback over increasing the number of seats. "And then it went back up and resumed the growth process again," says census historian Margo Anderson, author of The American Census: A Social History. There's nothing at all magical about the number 435 Congress settled on. That growth plateaued after the 1920 census, when Congress, for the first time in history, did not pass a new law about how to use the results of the latest national tally to reshape the House. "The apportionment system failed," explains Dan Bouk, an associate professor of history at Colgate University who has written a new report for the research institute Data & Society about how lawmakers in the 1920s ultimately shaped the House's current size.