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.

俄亥俄州和新墨西哥州自1990年以来一直是最具代表性的“晴雨表”州，在美国总统选举中，除了在1912年新墨西哥州尚未举行选举的三个选举外，均投票支持获胜的候选人。这一比例相当于在这一时期内，俄亥俄州成为了超过九成总统选举结果的指示器。在另一端，自1900年以来，邻近的阿拉巴马州和密西西比州的总统选举结果几乎如出一辙，两个州仅在45%的选举中投票支持获胜的候选人，这一比例仅为俄亥俄州的一半。华盛顿特区的情况也类似，投票支持民主党候选人的比例仅为47%，自1960年成为选举资格州以来，在该州的所有选举中均投票支持民主党候选人。