Apportionment and Polarization: The Effect of District Size in the US House

• In Event: Polarization in Legislative Politics

Abstract

The topic of district size was so important in the early American republic that even before it approved what would become the first amendment, the 1st Congress approved an amendment to limit the size of constituencies in the House of Representatives. In contrast to the amendment providing freedom of speech, assembly and religion, this earlier amendment dictating a ratio of representation failed to receive the requisite support among the states. Absent this constitutional provision, the number of representatives and thus district population is governed by statute, the most recent of which caps the size of the House of Representatives at 435. With over 300 million people living in the United States, each representative is responsible for more than 700,000 constituents.

The founding fathers were rightly concerned about how one person could provide adequate representation to so many people; however, the method of apportionment used by the United States has other ill-effects. In particular, we show that low levels of apportionment (a high ratio of constituents to representatives) exacerbates elite polarization. We show that increasing the population while holding constant the number of representatives can lead to more extreme legislators. We test this claim using Monte Carlo simulations of hypothetical districts under varying levels of apportionment. Using a computer algorithm we produce tens of thousands of alternative maps of congressional districts under existing levels of apportionment and under levels of apportionment in which there are fewer and more members of the House. Using this large set of hypothetical district maps, we find that as the number of representatives increases, the expected level of polarization decreases.

Authors

• Daniel Blyth Magleby, Binghamton University

• Gregory Robinson