What requirement did the Wesberry vs. Sanders case establish?

The Wesberry vs. Sanders case, decided in 1964, established the principle that U.S. congressional districts must be equal in population. This landmark decision arose from the issue of malapportionment, where some congressional districts were significantly larger or smaller in population than others. The Supreme Court ruled that this disparity violated the Equal Protection Clause of the Fourteenth Amendment, as it effectively diluted the votes of individuals in less populated districts compared to those in more populated districts.

The ruling emphasized the idea of "one person, one vote," reinforcing that every citizen's vote should carry the same weight in the electoral process. As a result, states are required to ensure that congressional districts are drawn in a manner that maintains approximately equal population sizes, thereby ensuring fair representation in Congress. This decision did not specifically address funding levels, geographical representation of state legislative districts, or the method by which districts are drawn, but rather focused explicitly on equal population representation in congressional districts.