Ohio State Route 66

The portion of SR 66 between Washington Avenue in Piqua and the Miami/Shelby County line is designated as the "Cpl. Samuel F. Pearson Memorial Highway",[2] in honor of a Piqua High School graduate who was killed at Camp Victory in Baghdad, Iraq, while serving in the Army Reserve, on October 10, 2007.[3][4]

SR 66 through Spencerville

• 1924 – Original route established.[5] Originally routed from Piqua to the Michigan state line 4 miles (6.4 km) north of Fayette.[6]
• 1931 – Truncated at Fayette; U.S. Route 127 replaced the route’s alignment from Fayette to the Michigan state line.[6]

SR 66 Truck is a truck route which bypasses a low railroad bridge along SR 66 in southern Defiance. Beginning at a signalized intersection with South Jefferson Avenue (SR 66), it heads west on Downs Street through a residential neighborhood. At South Clinton Street, SR 111, SR 111 Truck becomes concurrent with SR 66 Truck and both head northwest along Deatrick Street passing a supermarket and three sets of railroad tracks at-grade. At Baltimore Street (former SR 424), the two truck routes turn northeast onto Holgate Avenue paralleling the Maumee River. After heading through a residential neighborhood of the city, the road bends to the east and transitions to West Third Street. After passing under a railroad bridge, it passes numerous businesses and city facilities before reaching SR 111 again at the intersection of Third Street and Clinton Street. While SR 111 Truck ends, SR 66 Truck continues on South Clinton Street with SR 111 for one block before ending at SR 15/SR 18/SR 66.[8]