Nixon actually won the county in 1972. Of course, I think it give him his smallest margin out of any county in the state.
This is an old post (and this user has long since become inactive), but I wanted to correct this. Alachua County (Gainesville), was actually Nixon's worst county in the state that year; he won it against McGovern 57-43%. McGovern also broke 40% in Miami-Dade County, which he lost to Nixon 59-41%. Gadsden County was McGovern's third best county though, as he lost it to Nixon 61-39%.