Home > PA State Routes > Numbering System > Child Routes
State Route Numbering System
For example, consider the child routes of 45, following the route from the east end in Easton to the west end in Nanty Glo. In Treichlers, 45 met 145, which began to the south. A little further west, near Palmerton, 245 branched off 45. Further west, 45 met 345, which passed south of Shenandoah through Gilberton. A long way further west, 445 branches off in Millheim, and finally, 545 (now 26) met 45 in Pine Grove Mills south of State College. 645 and 745 were not initially assigned. Thus the x45 family fits the child route numbering rules.
Another example is 46, which has had a full family (146-746). Beginning at the south end in Emporium and moving north, 46 first encounters 146 near Colegrove, then 446 (out of order), 646 (out of order), 246, and 346. 446 and 646 initially did not reach south to 46, but later were extended southward. Thus 146-346 were initially signed in order from south to north according to the numbering rule. 546 intersected 346 but never 46. 746 was once signed as the part of current 646 south of 46. Thus the x46 family is fits the child route numbering rules by not requiring each x46 to intersect the parent route 46.
When the parent route was a three-digit number (e.g., 113, 115, and 320) the child routes were always greater than the parent route number (213-813, 215-715, and 420-520), mainly because the lower possible numbers were assigned to US highways (US 13, US 15, US 20-220).
In reference section of this look at the state numbering system, all the current and old state routes 1-799 have been arranged by the last two digits. Each route is shown as fitting or not fitting into the original family numbering system, and a brief amount of information is given to show where the route exists or once existed.
Use this section to look up any state route 1-799 and see if it was one of the routes of the original numbering system.
The child route numbering rules required that child routes be assigned sequentially by the hundreds digit without skipping any digit. For example, if 683 was assigned, then 83, 183, 283, 383, 483, and 583 should also be assigned. (Exceptions occur for families with three-digit parent routes.) In a few cases, a child route is predicted to exist but has not been noticed by the author, despite the effort in searching for the missing route.
On the other hand, not all possible child route numbers had to be used. For example, if 683 was assigned, then this fact says nothing about whether 783 was assigned. Thus numbers exist that may never have been used for route numbers.
These missing state routes are listed on the Missing Routes page.
x00: The null route 0 was never assigned, but there are routes ending in 00. These are not part of the family numbering system, but are the results of renumberings to avoid duplication with US and Interstate highways.
x06: There are no x06 child routes because 6 was eliminated and not part of the 1928 system. 106 and 706 exist because they replaced US 106. US 219 replaced 6.
x09: 409 appeared when child routes were numbered in the 1920s and 1930s, and 709 appeared in the 1940s, yet there is no relation to 9 (now US 20). On the other hand, 409 intersected US 309, so perhaps 409's number came from US 309. There are no other x09 routes because of the existence of US 209 and US 309 and because 9 was renumbered to US 20.
x11: Even though 11 (now US 40) was renumbered and US 11, US 111, and US 611 came to Pennsylvania, there was a 711 shown by the end of the 1920s. 711 was intended as the x11 part of the family route system, much like how 113 and 115 substituted for 13 and 15 because US 13 and US 15 existed. 611 came from US 611 and not as a child route of the x11 family.
x13: The x13 child routes are children of 113 rather than 13 because 13 was eliminated in 1928 to avoid duplication with US 13.
x14: 14 extends into New York as NY 14 and intersects NY 414, even though New York does not follow the family route system. The number 414 is likely a coincidence.
x15: 115 is the long parent route for the family. 15 was eliminated in 1928 to avoid duplication with US 15. There were no US x15 routes besides US 15, so the x15 family remains.
x19: There is no x19 family because 19 was eliminated in 1928 due to the existence of US 19, US 119, and US 219 in the state.
x20: US 20, US 120, and US 220 came to Pennsylvania. The result: a family of 320, 420, and 520 near Chester and Philadelphia, with 320 acting as a parent route.
x22: 22 was eliminated in 1928 in favor of 29 because of US 22, and so no x22 child routes were designated. 122-622 were used for US routes, too, leaving only 722 as a possible state route number. A 722 (intersecting US 222) was assigned near Lancaster.
x24: 124, 224, 324, and 624 are the child routes of 24, yet there is no evidence of 424 and 524. 624 was assigned only as a replacement for 224, which had to be renumbered when US 224 came to Pennsylvania.
x28: 128 and 228 are legitimate child routes, but 328, and 528 were assigned as though 8 was the parent route, and 428 may have been sequentially numbered off nearby 427.
x30: No parent route, so no child routes. US 30 and US 230 are the reasons why there was no x30 family.
x37: A trio of short routes near Greeley were numbered 37, 137, and 237. Curiously, an early 337 appeared near Warren for no apparent reason.
x40: 340 was assigned near Lancaster and is the parent route and only member of the x40 family, since US 40, US 140, and US 240 existed in the state.
x41: 41 had has the largest family: PA 41-741, DE 41-141.
x49: 549 begs to be part of the x49 family, but intersects none of 49-449, missing 49 by less than 10 miles. This fact suggests that 49 and 549 once intersected, but there is no evidence of this connection.
x55: The fact that 555 exists begs for 355 and 455 to have existed, but there is no evidence that those routes existed. The parent route was 55, now 120.
x56: 756 existed, but 556 and 656 appear to have never existed.
x57: 57 existed briefly but was renumbered 157 for no apparent reason.
x60: 6 gave way to 60 because US 6 was assigned, and 60 had a trio of child routes 160-360.
x62: US 62 was a later addition to the US highway system in Pennsylvania. 62 lasted until US 62 came but has an incomplete family: 162, 262, 562, and 662 existed, but there is no evidence of 362 or 462. The current 362 and 462 are later additions and not part of the family numbering system.
x65: 65 had no child routes and disappeared when US 62 replaced it.
x69: 69 had no child routes, perhaps because few routes were needed in the relatively remote part of the state that 69 served.
x70: The x70 family remains even though I-70 came to the state. Only 70 (now 171) was renumbered to avoid duplication with Interstates.
x71: This family (71 and 171) completely disappeared.
x75: 75 had no child routes.
x76: The x76 family was completely renumbered to avoid duplication with the I-x76 family.
x78: 78 had no child routes, even though 178-478 have existed.
x79: The entire x79 family (79 and 179) was renumbered to avoid duplication with the I-x79 family.
x80: Half of the x80 family was renumbered to avoid duplication with the I-x80 family. 380, 580, and 780 still exist.
x81: The majority of the x81 child routes remain despite the presence of I-81 in the state.
x83: Most of this family was renumbered to avoid duplication with the I-x83 family. 83 became 183, curiously in accordance with the renumbering rule associated with Interstates.
x84: 84 was renumbered to 287 to avoid duplication with I-84, and the child routes 184 and 284 remain.
x85: 85 may not have had any child routes, though 85 might have once intersected 185. 285 came from OH 85.
x86: 86 has been internally renumbered to SR 886 to avoid duplication with new I-86, but 86 is still signed as PA 86.
x89: 89 had the only initially segmented child route. 189 began in Pennsylvania, crossed into New York as NY 426, and returned to Pennsylvania as 189. Now all of 189 is 426.
x90: 90 was renumbered to 191 to avoid duplication with I-90, but the parts of the x90 family remain (390, 590, and 690).
x95: 95 had no child routes and was renumbered to 192 to avoid duplication with I-95. 295 is not part of the x95 family, and my need to be renumbered when I-295 comes to Pennsylvania.
x96: 96 had no child routes, but many of the x96 numbers have been used.
x97: 97 had no child routes.