I recently tested adding a list of the towns and cities that my client serves at the footer of one of their product pages with copy that went something like this:
[company name] supplies [product name] in the following areas: - I then listed around 35 cities and towns with high populations and was surprised to see that I got a page 1 ranking for about 1/3 of them.
Next step for me is to do something like Eric was recommending - especially for the more competitive locations like he said. Good luck!