State Route 66 (SR 66) is a north–south state highway in the northwestern portion of the U.S. state of Ohio. Its southern terminus is at U.S. Route 36 (US 36) in Piqua, and its northern terminus is at US 20 in Fayette. South of Defiance it generally follows the route of the former Miami and Erie Canal.

Quick Facts State Route 66, Route information ...

State Route 66
Route of SR 66 highlighted in red
Route information
Maintained by ODOT
Length	118.60 mi[1] (190.87 km)
Existed	1924–present
Major junctions
South end	US 36 in Piqua
Major intersections	US 33 in St. Marys US 30 near Delphos US 224 in Ottoville US 24 near Defiance US 6 near Evansport I-80 / I-90 / Ohio Turnpike near Archbold
North end	US 20 in Fayette
Location
Country	United States
State	Ohio
Counties	Miami, Shelby, Auglaize, Allen, Van Wert, Putnam, Paulding, Defiance, Williams, Henry, Fulton
Highway system
Ohio State Highway System Interstate US State Scenic
← SR 65 → SR 67

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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]

This section is in list format but may read better as prose. (April 2019)

• 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]