 Pennsylvania Route 166 | ||||
|---|---|---|---|---|
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| Route information | ||||
| Maintained by PennDOT | ||||
| Length | 21.9 mi[1] (35.2 km) | |||
| Major junctions | ||||
| South end |  US 119 in Point Marion | |||
 PA 21 in Masontown | ||||
| North end |  US 40 in Redstone Township | |||
| Location | ||||
| Country | United States | |||
| State | Pennsylvania | |||
| Counties | Fayette | |||
| Highway system | ||||
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Pennsylvania Route 166 (PA 166) is a north–south state highway in Fayette County, Pennsylvania. It follows the path of the Monongahela River along the entire western border of Fayette County.