Share of U.S. presidential elections where each state voted for the winner 1900-2020

Ohio and New Mexico have been the most consistent "bellwether" state for U.S. presidential elections, voting for the winning candidate in all but three of the 30 elections since 1990 (although elections did not take place in New Mexico until 1912). This equates to Ohio being an indicator of the result in over ninety percent of presidential elections over this period. On the other end of the spectrum, the outcomes in the neighboring states of Alabama and Mississippi have been almost identical in presidential since 1900, with both states voting for the winning candidate in just 45 percent of these elections; half the rate of Ohio. Washington D.C. has a similar rate of just 47 percent, voting for the Democratic nominee in every election since it became eligible in 1960.