U.S. Route 20 (US 20) is an east–west United States Numbered Highway in Pennsylvania, which clips the northwestern corner of the state, running entirely in Erie County. While it is part of the nation's longest road, it features the shortest segment of any two-digit U.S. Route in the commonwealth. Although bypassed by Interstate 90 (I-90) as the primary through route in the area, heavy traffic has led to nearly the entire highway being widened to four lanes in width.

US 20 travels for about 45 miles (72 km) through Pennsylvania's Great Lakes region. For most of its journey, it closely parallels a heavily traveled CSX Transportation rail line, which also serves Amtrak passenger trains. The highway enters the state under the moniker of West Ridge Road eastward from the Ohio border, as it journeys through Springfield Township, Girard Township, Fairview Township, and Millcreek Township. This section of road was widened to encompass a mostly four-lane setup after a pair of 1938 and 1946 infrastructural projects, owing to the heavy truck traffic between Erie and Cleveland, Ohio. A 1952 project saw the remainder of the Millcreek Township section of the route widened to four lanes.

At the intersection with Pennsylvania Route 832 (PA 832), just outside the Erie city limits, US 20 becomes West 26th Street. The highway then passes through an industrial and commercial corridor that represents a 1946 alignment change, which saw 26th Street extended to avoid the route's former complicated passage along East Avenue. Soon after a major interchange with Greengarden Boulevard, the highway becomes two lanes, as it passes through Erie's old residential neighborhoods. After a junction with US 19 just south of the city center, it becomes East 26th Street.

US 20 turns sharply northward as Broad Street at the Bayfront Connector, as it resumes four-lane status temporarily. It then turns east again as Buffalo Road through Wesleyville and Harborcreek Township. This portion of road was widened to four lanes during a 1958 overhaul. In North East Township, US 20 becomes West Main Road. Within the town limits of North East, it becomes West Main Street until it reaches the town center at its intersection with PA 89, where it becomes East Main Street. Outside the town limits, it becomes East Main Road until it reaches Pennsylvania's border with New York. The portion of road around North East was widened to four lanes in 1971.

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The entire route is in Erie County.

Location	mi	km	Destinations	Notes
Springfield Township	0.000	0.000	US 20 west / LECT west (Main Road) – Cleveland	Continues into Ohio
	1.479	2.380	PA 5 east / LECT east (Lake Road) / Great Lakes Seaway Trail – North Springfield	Western terminus of PA 5
	2.876	4.628	US 6N east to I-90 – Albion, Meadville, Warren	Western terminus of US 6N
	6.224	10.017	PA 215 to I-90 – North Springfield
Girard Township	10.351	16.658	PA 18 south (Meadville Road) to I-90	West end of PA 18 concurrency
Girard	11.375	18.306	PA 18 north (Rice Avenue)	East end of PA 18 concurrency
Fairview	15.419	24.814	PA 98 (Avonia Road) to I-90
Millcreek Township	22.739	36.595	PA 832 (Sterrettania Road/Peninsula Road) – Presque Isle State Park
Erie	23.655	38.069	I-79 – Bayfront, Pittsburgh	Stack interchange
	26.381	42.456	US 19 south (Peach Street) – Edinboro, Meadville, Pittsburgh	Northern terminus of US 19
	26.459	42.582	PA 505 south (State Street) to I-90 – Waterford, Union City	Northern terminus of PA 505
	26.953	43.377	PA 8 south (Parade Street)	Northern terminus of PA 8, 2 blocks north of PA 97 northern terminus
	28.333	45.598	PA 290 (Bayfront Connector)	Interchange
Wesleyville	30.325	48.803	PA 430 east (Hannon Road) to I-90	Western terminus of PA 430
Harborcreek Township	33.898	54.554	PA 531 south (Depot Road) to I-90	Northern terminus of PA 531
	34.131	54.929	PA 955 west (Iroquois Avenue)	Eastern terminus of PA 955
North East	41.201	66.307	PA 89 (Lake Street) to I-90
North East Township	44.244– 44.269	71.204– 71.244	I-90 – Erie, Buffalo	Partial cloverleaf interchange
	45.433	73.117	US 20 east (West Main Street) – Buffalo	Continues into New York
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

• U.S. Roads portal
• Pennsylvania portal

• Pennsylvania Highways: US 20
• US 20 at AARoads.com
• Pennsylvania Roads – US 20

U.S. Route 20
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