Reuters, via Yahoo!, reports on Why do Americans vote on Tuesday?

U.S. elections have been held on the first Tuesday in November since 1845, when Congress first agreed on a nationally uniform date.

Their choice of Tuesday was probably based on convenience… Friday or Monday would have been the beginning or end of the working week, when accounts needed to be opened or settled. Saturday or Sunday might have conflicted with worship services.

[The] middle-of-the-week date didn’t interfere with commerce and didn’t interfere with religious purposes.