Charitable gifts aren't isolated transactions. Every gift comes out of a social context. Donors think a lot about what others know and believe and say when they decide to give.
The Return Customer recently took a look at this in a commercial context at The Power of Localized Social Proof:
When you use localized social proof, customers start to trust you because someone they trust (at your company, in your industry, from your hometown) already trusts you. This borrowed trust is a great foundation upon which to build a relationship with a potential customer. It opens the doors for opportunities you didn't previously have.
Even implied localized social proof can improve fundraising results. Just mentioning the donor's city name, as in Join the Seattle campaign against hunger, where the city name is pulled from the donor's record, can improve fundraising results. I've seen that happen many times.
If your cause is local, don't get tired to keeping that fact in front of donors. If you aren't local, look for ways to localize it.