Yes, it's +1 per turn (not per roll, and it doesn't count on the turn you take the territory) for every city territory you have. So if I take over all of California, for example, I'll have a +7 bonus each turn, which as game master, I would divide as 4 territories in the first roll and 3 territories in the second if I make one.
*2nd roll for TLOMAH, expanding northward
*2nd roll for TLOMAH, expanding northward