Mooresville may be Race City USA and, yes, stock car racing has its roots in the N.C. foothills, but a number of other states have been quietly working to lure the industry away from here with sweet economic incentives. And for good reason: Seventeen years ago, when the last economic impact study on motorsports was done, the industry did a $500 million per year business in North Carolina. Another study is about to be done, and the numbers are certain to far surpass that. If North Carolina ultimately strengthens its grip on motorsports by fending off the overtures of other...