By Greg Bishop Known as TrackTown USA, Eugene has a storied history—and a swanky updated stadium—to win over track fans. Now it aims to win over U.S. sports fans, too. The messy perch that runners flock to sits about 110 miles south of Portland. Drive past the wineries and farms and billboards and dispensaries—so many dispensaries—along with the sign that proclaims Linn County the “grass seed capital of the world.” Exit here, banking into this city of roughly 170,000, with the perfect nickname, TrackTown USA, for an ongoing and unprecedented event. Head east, up the hill from downtown. Turn on…