Authors:

There is a study that shows that people who were asked their political opinions, when there was a picture of the American flag in the corner of the questionnaire, reported more favorable attitudes toward Republican Party positions, because the flag is typically associated in people's minds with a Republican belief set. If people vote at a polling place inside a church, they vote more Republican. If they vote at a polling place inside a school, they vote more Democrat.

Source: www.pbs.org
There is a study that shows that people who were asked their political opinions, when there was a picture of the American flag in the corner of the questionnaire, reported more favorable attitudes toward Republican