The latter-day Cannonball may well have been named for the song, but I don't see any reliable evidence that the song predated the train of ca1882-ca1904.

There's a wealth of information here:

http://www.bluegrassmessengers.com/wabash-cannonball--1882-lyrics.aspx

I can't agree, however, with the claim that the "Cannonball" owes much, if anything, to the Hutchison family's "Uncle Sam's Farm" (1848). The tunes are also entirely different.