Politically, Hamilton County is conservative. Along with the rest of East Tennessee, it has been supportive of the Republican party since the Civil War, even as the rest of the Solid South voted staunchly Democratic. However, unlike most counties in East Tennessee, Hamilton County is a strong two party county, with the Democratic candidate usually receiving at least 40% of the popular vote in presidential elections, and the city of Chattanooga tending to lean Democratic. In 2004, Republican George Bush defeated Democrat John Kerry 57% to 41%. The last Democrat to win the county was Harry S. Truman in 1948, although George Wallace did win a plurality in 1968.
In 2008, Republican John McCain defeated Democrat Barack Obama by a slightly smaller margin of 55% to 43%. In 2012, Republican Mitt Romney defeated incumbent Obama by a margin of 56% to 42%. Four years later in 2016, in businessman Donald Trump's sweep of Appalachia, Hamilton County furnished the GOP with a mildly increased margin of 55% to 39% for Secretary of State Hillary Clinton. In 2020, eventual winner Joe Biden received the highest percentage of the popular vote of any Democratic presidential candidate since Jimmy Carter in 1976.