SPRINGFIELD, Ill. — Visitors to this year’s Illinois State Fair will be able to visit one of the nation’s more historic highways with the Route 66 Experience. The multiyear project will turn the Springfield fairgrounds’ Gate 2 into a year-round destination with a microform of the Mother Road in Illinois, from Chicago to the Mississippi River in Madison. The Illinois Route 66 Scenic Byway is sponsoring the plan. Executive director Casey Wichmann says it will have the first phase completed by the state fair’s opening Aug. 12. Construction of the highway, one of the nation’s first interstate “hard roads,” was begun 95 years ago.