Secret SR numbers in North Carolina? Or something else?

[Dirt Roads]

Last summer, I noticed that NCDOT District 7 had installed some of the new [streetblades] along Guess Road (NC-157) in Northern Orange County, but they were marked as SR-1003 instead of NC-157.  Traveling on NC-57 today, I saw the new [streetblades] at the four-way stop in Caldwell that were marked "SR-1003 Guess Road" to the right (southeast) and marked "NC-157" to the left.  On the way back, I detoured down the Guess Road section and sure enough, all but two intersections in Orange County had the newer [streetblades] marked as SR-1003, plus a third one off a private park that mimicked the old [streetblades].  But I was surprised when I entered Durham County that all of the [streetblades] also said "SR-1003 Guess Road", and many of these were the old style. 

Makes me wonder if SR-1003 is a not-so-secret number for NC-157.  Additionally, I was surprised that the SR-1003 designation crossed into Durham, which is in NCDOT District 5.  I turned south onto St. Marys Road to get back to Hillsborough, and sure enough, its SR-1002 is also carried over between Durham County and Orange County.

For those not familiar, the SR-1000 series in each county are typically the "main roads", and the higher numbers are clustered (SR-1100 series is in Hillsborough, SR-1300 series is in Efland, etc.)  There does seem to be a pattern of "missing" numbers in the SR-1000 series in the counties around us.  Additionally, Orange County has so few "main roads" that there are not very many SR-1000 series numbers in use.  Throughout most of North Carolina, it is common for most of the U.S. and state routes to have [streetblades] with the highway number and no other street name.  For instance, NC-57 has [streetblades] marked as "NC-157" or "Hwy 57" throughout.  Most of those have no other information, but some have a small double arrow.

One other thought.  NC-157 runs parallel to US-501 from Roxboro to Durham, and it ends abruptly at the Guess Road exit on I-85.  Guess Road continues unnumbered to the Northgate Mall area and changes into Buchanan Boulevard (one of the border streets for the original Duke University campus, now the East campus).  There was a solitary trailblazer for "South NC-157" just beyond the four-way stop at Caldwell, then no trailblazers in either direction to St. Marys Road.  There are a few newer ones around the I-85 exit, but hardly any elsewhere in Durham or Durham County.  Perhaps NCDOT is planning to eventually decommission all of NC-157 south of Caldwell now that it is fully marked as Guess Road.

[74/171FAN]

Well NC 157 south of Caldwell was previously SR 1003.  It sounds just as likely that someone designing streetblades decided to use SR 1003 for some reason.

[Mapmikey]

SR 1003 was the designation before NC 157 was placed on this road in 1987.

Long-time state highways definitely do not have secret 10xx designations like this.

I poked around on street view and found street blades as early as 2014 with this, including one that calls it SR 1322 instead.

[fillup420]

Yea and north of there, where NC 157 turns right to continue north is called by SR numbers on both street blades. I guess no one could be bothered to update the signs