Beginning in the 1960s and 1970s, the Supreme Court began to establish and enforce a constitutional requirement for the apportionment of legislative districts at the national, state, and local levels. This requirement, the “one person, one vote” principle, has become a benchmark of the constitutional jurisprudence as well as a conceptualization of the fundamental democratic norm of political equality. Since these early cases, apportionment plans that violate this constitutional requirementeven with levels of intrastate malapportionment of less than 1%have been held to be unconstitutional. Yet, there is a much more severe form of malapportionment that continues today and will worsen with the reapportionment of the United States House of Representatives after the 2010 Census: interstate malapportionment. The levels of interstate malapportionment are over 9,000% greater than the levels of intrastate malapportionment already found unconstitutional. This Article explores the causes and possible solutions to this problem. It concludes that the constitutional requirement of “one person, one vote” can only be constitutionally addressedto any considerable degreeby reconsidering the twentieth century statutory requirement that fixed the size of the House at 435 seats.