US 87 in the panhandle

[texaskdog]

It exits I-27 near Happy and then again at Tulia.  South of there however it stays with I-27, even signed, while it instead has a business I-27.  Why the inconsistency?

[txstateends]

I would guess it's the length of mileage in each segment.  The US 87 segments from Canyon-Happy and from Tulia-Kress are longer than the Biz I-27 in-town Plainview and in-town Hale Center ones are, and the Plainview and Hale Center segments are almost entirely in-town segments.  If Canyon, Happy, Tulia, and Kress had just short individual in-town segments off of I-27, they would probably be labeled Biz I-27.  That's my guess, I've never heard definitively.

[wxfree]

I agree with the previous guess.  However, in one case the answer is clear.  The business route in Plainview is one of the original business routes, established in the 1990 minute order making that designation official for loops that had signed as business routes.  The one in Hale Center was an upgrade from a city street made in 2002.  The minute order describes the need for immediate improvements due to the street's bad condition.  It would appear that US 87 ran along Main St. at some point and was moved either before or when I-27 opened, but Main St. was neither US 87 nor a loop that replaced its original route when the designation was established.  This is an interesting example of a non-state route upgrade to a business route, probably because it just naturally fits as one, moreso than as a loop.