Business routes of Interstate 25
Interstate business routes are roads connecting a central or commercial district of a city or town with an Interstate bypass. These roads typically follow along local streets often along a former US or state highway that had been replaced by an Interstate. Interstate business route reassurance markers are signed as either loops or spurs using a green shield shaped sign and numbered like the shield of the parent Interstate Highway.
Along Interstate 25, business routes are found in all three states through which I-25 passes: New Mexico, Colorado, and Wyoming. Some states regard Interstate business routes as fully integrated within their state highway system while other states consider them to be either local roads to be maintained by county or municipal authorities or a hybrid of state and local control. Every state along I-25 regards its business routes as fully incorporated members of their respective state maintained highway systems.
Although the public may differentiate between different business routes by the number of the parent route and the location of the route, there is no uniform naming convention. Each state highway department internally uses its own designations to identify segments within its jurisdiction.
New Mexico
All the business loops within New Mexico are maintained by the New Mexico Department of Transportation. In New Mexico, Interstate business routes are named independently of their parent Interstate's designation with business loops of I-25 numbered between 10 and 19, those of I-10 between 20 and 29, and those of I-40 between 30 and 39. New Mexico business loop numbers ascend eastward and northward with gaps in numbering to allow for future designations. I-25 begins with a business route through Williamsburg and Truth or Consequences before proceeding northward with additional routes serving the towns of Socorro, Belen, Las Vegas, Springer, and Raton. These routes largely conform to the current or former alignment of the unsigned US Highway 85 through these communities before the construction of I-25. NMDOT has decommissioned US 85 throughout the state and no longer signs the highway along its length, as US 85 entirely follows I-25 with the single exception of the business loop in Las Vegas. The American Association of State Highway and Transportation Officials, however, continues to recognize the New Mexico portion of US 85 maintaining continuity with sections in adjacent states.Williamsburg–Truth or Consequences business loop
Interstate 25 Business, inventoried as Business Loop 11, is a business loop serving the cities of Williamsburg and Truth or Consequences in Sierra County. The loop begins at exit 75 of I-25 in Williamsburg, intersecting State Road 187, traveling northeast on Broadway Street through Truth or Consequences until meeting Main Avenue. Between that point and Date Street, the route follows two one-way roads with Broadway carrying northbound traffic and Main conveying traffic to the south. The routes combine and turn north on Date Street, intersecting the western terminus of NM 51. Turning northwest, the highway intersects NM 181 and terminates at exit 79 on I-25 on the north side of Truth or Consequences.Most of the loop, with the exception of its I-25 interchanges, was previously part of US 85, which joined the route from the south at NM 187 and departed to the north along NM 181.
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Socorro business loop
Interstate 25 Business, inventoried as Business Loop 12, is a business loop serving the city of Socorro in Socorro County. The loop begins at exit 147 of I-25 and travels northwest along California Avenue until an intersection with the northern terminus of NM 1. The loop turns north as a divided highway as it enters the city. US 60 intersects from the west, and the loop becomes concurrent with US 60 as the pair of highways continue to the north. The loop terminates at exit 150 on I-25, and US 60 continues along the Interstate as it exits Socorro.;Major intersections
Belen business loop
Interstate 25 Business, inventoried as Business Loop 13, is a business loop serving the city of Belen in Valencia County. The loop begins at exit 190 on I-25 and intersects the northern terminus of NM 116 as the highway travels north along Main Street into the city. The western terminus of NM 309 is met in central Belen. The loop continues north to NM 314 then turns northwest before terminating at exit 195 on I-25.;Major intersections
Santa Fe business loop
Interstate 25 Business, inventoried as Business Loop 14, was a business loop that served Santa Fe in Santa Fe County. The loop began at exit 278 on I-25 and traveled northeast along NM 14. It then went east on NM 466, cutting through the south side of Santa Fe. The road ended up as Old Pecos Trail and remained so until reaching I-25 again and terminating at exit 284. The route was decommissioned.;Major intersections
Las Vegas business loop
Interstate 25 Business, inventoried as Business Loop 15, is a business loop serving Las Vegas in San Miguel County. It also carries unsigned US 85. The loop begins at exit 343 of and travels northeast, intersecting NM 329. The loop continues north, passing to the west of Las Vegas station served by the Southwest Chief line of Amtrak, just south of the intersection with NM 104. Continuing north, the highway passes east of Municipal Park before terminating at NM 250 and I-25 at exit 347.;Major intersections
Springer business loop
Interstate 25 Business, inventoried as Business Loop 16, is an unsigned business loop serving the city of Springer in Colfax County. The loop begins at exit 412 of I-25 and travels northeast along Railroad Avenue. The loop serves as the main north–south road in the town and intersects Fourth Street, which, to the west of the loop, is NM 21 and, to the east, is US 56 and US 412. Continuing northwest, the loop intersects NM 468 and then runs closely parallel to the Interstate before merging at exit 414.;Major intersections
Raton business loop
Interstate 25 Business, inventoried as Business Loop 17, is a business loop that begins at exit 450 on I-25 south of Raton in Colfax County concurrent with US 64. The two highways intersect NM 555 then pass east of La Mesa Park, traveling along Second Street north into the city. Clayton Road takes US 64 off of the loop to the east as the loop continues north, crossing over the rail line that serves Raton station before turning northwest and terminating at exit 454 on I-25.;Major intersections
Colorado
All Interstate business routes in Colorado are maintained by the Colorado Department of Transportation. Within Colorado, all highways maintained by the state are classified as state highways, including Interstates and US Highways which hold the same numerical designations as their nationally established routes. The numerical values of all state highway names are followed by an alphabetic suffix, although this convention is used by the department internally and not reflected in route signage. Hence, the mainline of I-25 throughout the length of the state is classified as State Highway 25A while its two business routes in Aguilar and Walsenburg are internally named SH 25B and SH 25C, respectively. US 85 and US 87 are hidden routes not recognized nor signed by CDOT in southern Colorado. They are, however, established AASHTO routes maintaining continuity with signed portions in other states along their routes. In southern Colorado, the routes primarily follow I-25, including at Aguilar, but with deviations, such as along the Walsenburg business route. In addition to these, US 160 joins I-25 at Walsenburg and follows concurrently with the Interstate to Trinidad, including the portion bypassing Aguilar. Thus, in Walsenburg, US 160 crosses the business route in the town center and again at the business route's southern terminus.Trinidad business loop
Interstate 25 Business, inventoried as State Highway 25A, was a business route of I-25 that connected Trinidad in Las Animas County to the Interstate. The route began as Animas Street, coming from University Street at a diamond interchange at exit 13 on I-25. The route was concurrent with US 160 along Main Street. The route turned southwest on Main Street and terminated at I-25. In 2009, a reconstruction project involved a replacement of the northbound viaduct crossing the Purgatoire River and more reconstruction in 2011, adding a new diamond interchange at Main Street and I-25 and replacing the antiquated ramps at Animas and University streets, which ultimately eliminated the route.;Major intersections
Aguilar business spur
Interstate 25 Business, inventoried as State Highway 25B, is a business spur of I-25 connecting the town of Aguilar in Las Animas County to the Interstate. The route begins at the corner of Main and Fir streets in Aguilar. The spur proceeds for one block north along North Fir Street before turning to the northwest along Lynn Road away from town. The route turns east along County Road 60 immediately before terminating at I-25 exit 34.;Major intersections
Walsenburg business loop
Interstate 25 Business, inventoried as State Highway 25C, is a business loop of I-25 serving the town of Walsenburg in Huerfano County. The route begins at I-25 exit 49 and proceeds to the west along the southern edge of Walsenburg. The route then turns to the northwest along Walsen Avenue. At Seventh Street, US 160 intersects from the west US 160 runs concurrently with the loop until US 160 turns off to the east along Fifth Street to I-25. The loop then continues northeast along Walsen Avenue, leaving town, and intersects SH 69 before terminating at I-25 exit 52.CDOT does not recognize or sign US 85 in the southernmost part of its route within the state, nor does it recognize US 87 anywhere within Colorado, as they are redundant with other routes in the state highway system. The highways remain established by AASHTO primarily along I-25 in southern Colorado and along Walsenburg's I-25 business route.
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