US 422 in Pennsylvania, and specifically its mileposts

[Michael in Philly]

All right, I'm stumped.

I just drove home from the Harrisburg area using US 422.  On the expressway section that begins just west of Pottstown and ends at King of Prussia, there are mileposts, starting (eastbound) at about 168-1/10 (and they do have the tenths written out as fractions, not ".1")

For those unfamiliar, 422 eastbound begins at Cleveland and enters Pennsylvania east of Youngstown.  It then runs east-southeast, passing north of Pittsburgh, until it meets US 22 near Ebensburg (in the same county Johnstown is in).  It is then neither seen nor heard of until it reappears at Hershey, east of Harrisburg, branching off US 322.

I couldn't imagine what I could be 168 miles from.  Certainly not Hershey (it's 50 miles, maybe a little more), or the Ohio line (250 or so in that case).  My first thought was that for some reason they started the mileposts at the west end of the gap, thus including the gap.  But that didn't make a lot of sense.  Could it be the total mileage of the two segments, from the Ohio line to Ebensburg and then from Hershey east?

Incidentally, it's now fairly common to see mileposts on limited-access sections of US highways in Pennsylvania, clearly reflecting the mileage of the whole route (or the whole Pennsylvania portion of the route).  US 30 between York and Lancaster, for example, has mileposts in the mid-200s, presumably representing the distance from the West Virginia line west of Pittsburgh.

Besides that specific question, what does anyone know about the history - how did that gap happen?

[NE2]

Besides that specific question, what does anyone know about the history - how did that gap happen?

http://www.fhwa.dot.gov/infrastructure/us22.cfm

[Michael in Philly]

How bizarre!
And thanks - I didn't know about that history source.
Is there any other US route that does that, besides US 2?

[hbelkins]

For those unfamiliar, 422 eastbound begins at Cleveland and enters Pennsylvania east of Youngstown.  It then runs east-southeast, passing north of Pittsburgh, until it meets US 22 near Ebensburg (in the same county Johnstown is in).  It is then neither seen nor heard of until it reappears at Hershey, east of Harrisburg, branching off US 322.

Picking a nit ... the Ebensburg end of US 422 is at US 219. An "End" sign is posted and US 422 is not signed through downtown or where the route either meets old US 22 in downtown or new US 22 on the southeast side of town.

[Michael in Philly]

^^Which would be an argument against the they're-counting-the-mileage-in-the-gap theory, because I've always assumed 422 was legally there but "hidden" under 22 and 322.  If it ends at 219, the route from Ebensburg to Hershey is less obvious.  At least not obvious enough to be measured in tenths of miles.

[agentsteel53]

How bizarre!
And thanks - I didn't know about that history source.
Is there any other US route that does that, besides US 2?

US-85 officially does not exist in New Mexico.  US-87 officially does not exist in Colorado.  Both are under I-25.

there is one sign for each in each state.  US-87 is randomly signed on one mainline reassurance marker going northbound in Denver.  US-85 has a surviving shield in downtown Albuquerque from before it was decommissioned in 1991.

(in New Mexico there are also plenty of historical markers which show US-80, US-85, etc, as those are less frequently updated.)

[NE2]

US-85 officially does not exist in New Mexico.  US-87 officially does not exist in Colorado.  Both are under I-25.

There's a difference here in that AASHTO inventories them as continuous routes.

More similar to the case of US 422 are the routes through Yellowstone.

[treichard]

The mileposts are also interesting for US 22/US 322 just north of I-81 near Harrisburg.  There are separate, alternating milemarkers with US 22 and US 322 shields, but both have identical distances from a single western zeropoint, even though their routes have different lengths.

When the US highway numbers were assigned to PA state routes in the mid-1920s, PA was annoyed that their cross-state routes (with a single state number) were given a series of US numbers instead of a single US number.  They tried to remedy this in a few places, and replacing the majority of PA 17 (Benjamin Franklin Highway) with US 422 was one "fix."  But for whatever reason, old US 22/PA 3/PA 5/PA 17 in the present US 422 gap didn't get the US 422 number added as well, even though most of PA 3 became US 22 earlier,  most of PA 5 became US 322 later, and most of the rest of PA 17 became US 422.

Here is how it looked (as best as I can reconstuct) in 1928:
http://www.m-plex.com/roads/maps/paus1928map.gif

[NE2]

Tim, I tried to contact you a while back about some of those question marks, but your email was dead. What's your current email?