Location Referencing System (Pennsylvania)

Pennsylvania State Route System
Route markers for Interstate 76, U.S. Route 6, Pennsylvania Route 18, and State Route 3069
System information
Notes	Numbers are assigned through Location Referencing System; all routes are assigned quadrant numbers, State Route X (SR X), which usually corresponded to the signed numbers of traffic routes (PA X). State Routes are generally state-maintained.
Highway names
Interstates	Interstate X (I-X)
US Highways	U.S. Route X (US X)
State	Pennsylvania Route X (PA X)
Quadrant Routes:	State Route X (SR X)
System links
Pennsylvania State Route System Interstate US State Scenic Byways Legislative

Numbers are assigned through Location Referencing System; all routes are assigned quadrant numbers, State Route X (SR X), which usually corresponded to the signed numbers of traffic routes (PA X).

In the U.S. state of Pennsylvania, state highways are maintained by the Pennsylvania Department of Transportation. Each is assigned a four-digit State Route (SR) number in the present Location Referencing System. Traffic Routes are signed as Interstate Highways, U.S. Routes and Pennsylvania Routes (PA Routes), and are prefixed with one to three zeroes to give a four-digit number. PA Routes are also called Pennsylvania Traffic Routes, and formerly State Highway Routes.

The Pennsylvania State Route System was established by the Sproul Road Bill passed in 1911. The system took control of over 4,000 miles of road. The system of roads continued to grow over the next few decades until continual addition of roads faced greater opposition. On October 1, 1940, the Pennsylvania Turnpike's first section of highway was opened to motorized traffic; the Turnpike operated under the Pennsylvania Turnpike Commission and was independent of the then-known Department of Highways.

In 1970, the Department of Highways and several other offices and departments were reorganized into the Pennsylvania Department of Transportation. In 1987, the Sproul system of Legislative Routes was reorganized into the current Pennsylvania State Route System under the Location Referencing System.

In 2013, PennDOT posted weight restrictions on several bridges along the state route system. As a result, several truck routes were signed for U.S. and state routes, bypassing these weight restricted bridges. Signage practices for these truck routes vary by district, with some districts such as District 5 signing them as standard truck routes and others such as District 6 signing them as double-bannered "alternate truck" routes.

The symbol used for the signage of state routes is an outline of the keystone after Pennsylvania's nickname. Four-digit State Routes are unsigned, except on small white reference markers at intersections, and are only unique within each county. Underneath, there is a larger typeface number identifying the segment of highway being entered. Segments are typically one half mile long and are usually numbered in multiples of 10 on non-Interstate highways. Segment numbers increase in the north or east direction, and are even-numbered on undivided highways and on the northbound or eastbound direction of divided highways.