After a bypass around downtown Farmington was built, it was originally designated as New Mexico state route 5001, with US 64 remaining as a route through downtown on Broadway. The 5001 designation may have been a follow-on to a San Juan County highway with the same route number.
However, when these photos were taken in May 2004, I found that the bypass is signed as US 64, with the former route of US 64 through downtown Farmington becoming Business US 64.
But the official 2007 New Mexico Transportation Map still shows NM 5001 bypassing downtown Farmington with US 64 going through downtown Farmington. The New Mexico Department of Transportation's state highway route log also includes this description for NM 5001:
From Jct US 64 (West Main Street) in Farmington, south on the Murray thru-way and east on the old Bloomfield Highway, to end at Jct US 64 (Bloomfield Blvd.).
NMDOT's US highway route log does not have a detailed description of the route of US 64 through Farmington. Checking through the minutes of AASHTO's Standing Committee on Highways, which governs numbering of U.S. routes, including business routes, shows no indication of a business route for US 64 in Farmington.
So, as far as I can tell, in Farmington, the marked route of US 64 may really be NM 5001, and Business US 64 is the actual US 64!
The routes are not well-marked away from the intersection of the two US 64's. As a consequence, when I visited the area in May 2004, I got lost by taking the marked US 64 when I should have taken what was marked as the business route. I did not see any markers for NM 5001. At the time, I assumed that the route had been replaced. Judging by the official maps and logs, though, NM 5001 is still on the books.
The signs for the intersection of the two versions of US 64 on the east side of the city (left) may add to the confusion, because they refer to US 64 as a "truck bypass" (which appears to be its actual status).
Look closely at the sign for "Downtown Farmington" (right) and you'll see something else -- a designation as "Business Loop" 64. This is the only shield of its kind in the area. All other markers for Business US 64 refer to it as "Business" 64, including a similar sign assembly west of downtown Farmington where the two routes rejoin.
One thing hasn't changed -- the bypass has retained its city street name of Murray Drive.