From the American Civil War until the mid-20th century, Philadelphia was a bastion of the Republican Party, which arose from the staunch pro-Northern views of Philadelphia residents during and after the war (Philadelphia was chosen as the host city for the first Republican National Convention in 1856). After the Great Depression, Democratic registrations increased, but the city was not carried by Democrat Franklin D. Roosevelt in his landslide victory of 1932 (in which Pennsylvania was one of the few states won by Republican Herbert Hoover). Four years later, however, voter turnout surged and the city finally flipped to the Democrats. Roosevelt carried Philadelphia with over 60% of the vote in 1936. The city has remained loyally Democratic in every presidential election since. It is now one of the most Democratic in the country; in 2008, Democrat Barack Obama drew 83% of the city's vote. Obama's win was even greater in 2012, capturing 85% of the vote.

What party dominated until the mid-20th century