And, yes, Jacksonville should have been on the list. (It's actually the 14th biggest city in the U.S.)
I think that's only because the city proper is expanded to take up almost all of Duval county though, so it includes lots of areas which are really suburban or even rural.
Yeah, I think it actually has the largest land area of any city in the continental U.S.
How large is it? I know El Paso, TX has a huge land area as well most of it uninhabited desert.
From the census...
City Miles Rank
Anchorage city, AK 1,697.2 1
Jacksonville city, FL 757.7 2
El Paso city, TX 249.1 20