When an employee files for unemployment, do they file in the state they worked or the state they live?

The company I work for is a construction company and our employees can work in multiple states. I sometimes get multiple claims for the same person for different states... are they allowed to collect from more then one!

It prob varies from state to state. A friend of mine was laid off from his job in MD and lived in WV. He filed in WV but then everything started coming from MD and he dealt with MD for however many months he was in the situation.
I think employers pay into a fund in the state they employ people in. That provides somes of the funds to pay the laid off employee regardless of where he lives.
I am not an expert on this subject. There also may be agreements between different states that govern.