http://www.okladot.state.ok.us/maps/county/index.htm
It includes new(er) county maps than were previously on the site. I have the old PDF files for all 77 counties stored on my hard drive if anybody wants them.
I uploaded a zip file with all the old style maps here:
https://www.dropbox.com/s/h1dvd0xph09aqpf/oklahomacountymaps.zip
Also, this really should be in the Central States board. I don't know what I was thinking when I posted it here.