It doesn't exist as far as I know because of several reasons:
1) it would be a PITA to assemble and maintain and none of us are paid to contribute here
2) it would be changing all the time as clients come and go
3) as an experienced shopper I might readily be able to see shops in Nebraska that new shoppers in Nebraska could not see
4) it is hard enough keeping track of the companies that have clients in my own state and I am constantly surprised when I get an email from a company I have not worked with in years that suddenly they have a client in my back yard.
If you are a beginning shopper, start off registering with Bare, Market Force and Steri-cycle because these companies do have good beginning shops in every state in the union. If you find that shopping works for you, then set aside a few evenings to register with every company on the list provided at the bottom of each page here. Make sure you sign up for emails from them because once you have found a few that shop your area by your own exploration you will be able to add to that list as companies get clients near you. It cuts down on the need to check each company's website job board frequently.