Regional versus national keywords

How do I run two capaigns without ad appearing twice?

[jim_o]

Regional campaign keyword is:
foundation repair

In national campaign, to get local people without a local ISP, i would like to have keyword + city

My concern that:
when person enters foundation repair milwaukee

That both the national and regional ads will appear.
How do I prevent that from happening?
Thanks for the help.
Jim

[jim_o]

I neglected to say that this is in my adwords regional versus national campaign and not general web site keywords..