Signage 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 near physical features such as intersections and bridges, and are 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.
Circumstances with some routes Special routes are not assigned State Route numbers corresponding to their signed numbers but are instead marked along other routes, mostly Quadrant Routes.
Concurrencies are assigned a number equal to the smaller number of the concurrent routes, or the highest type (Quadrant Route → PA Route → U.S. Route → Interstate). Occasionally, a signed Traffic Route number does not match the State Route, usually in the case of an extension or relocation. (One example is
Pennsylvania Route 3, which uses a
one-way pair of Quadrant Routes in
Center City Philadelphia.) A different number can also be used to avoid conflicts between different types — for instance, signed
Pennsylvania Route 380 is actually
State Route 400, renumbered ca. 1973 when
Interstate 81E was renumbered
Interstate 380. The majority of, but not all, signed Traffic Routes are state-maintained. ==Lists of routes==