An intrastate route at just 63.35 miles in length, Interstate 19 begins in the city of Nogales, just north of the U.S./Mexico border. The freeway initially heads west before curving north along the Santa Cruz River all the way to Tucson. Along this historic river valley, the freeway passes Tumacacori National Monument, site of a historic Spanish mission, as well as travelling through Green Valley, Sahuarita, and the San Xavier Indian Reservation. Interstate 19 then enters the south side of Tucson, and travels directly north to meet Interstate 10 just south of downtown. Interstate 19 directly replaced U.S. 89, and retained the milepost numbering of the U.S. highway.

As part of the original design, ADOT received a waiver from Interstate Highway requirements to allow Interstate 19 to end in Nogales, rather than at the border. This was due to the topography of the Nogales area, and the disruption that the freeway would cause to the central business district, as discussed in a 1964 public meeting. The community wanted the freeway to end where Business Loop 19 branches off (at Kilometer 8), or failing that, to be routed along the course of present-day Arizona 189 to the Border. The final decision led to the route taking the path it does today - the preferred alternative of the engineers.

Ironically, in 2008, talks were held to discuss rerouting Interstate 19 away from the Central Business District of Nogales due to the traffic issues at the border.

Interstate 19 reflects design trends apparent during the construction period. The freeway was designed during the Lady Bird Johnson highway beautification era, and reflects it through the detailed landscaping and extra-wide median.

Interstate 19 is also unique for being the longest highway and only Interstate highway signed in Metric. The signs were placed in May 1979 with the completion of the freeway under a test program with the Federal Highway Administration.

In 2004, ADOT announced that the signs were to be converted to English units, and replaced several signs around the Interstate 10/19 interchange. However, in 2008, a new metric sign was placed outside Green Valley on Southbound Interstate 19.

In 2009, ADOT announced that federal stimulus money would be used to re-sign the freeway, including renumbering all exits. Once this work is completed, AARoads will travel the freeway to replace all photos.

Construction Timeline:

  • Km 0 - 4 (Nogales - Mariposa Ave): 1971
  • Km 4 - 8 (Mariposa Ave - Business Loop 19): 1968
  • Km 8 - 17 (Business Loop 19 - Rio Rico Dr): 1968
  • Km 17 - 25 (Rio Rico Dr - Palo Parado Rd): 1966
  • Km 25 - 33 (Palo Parado Rd - Tubac): 1978
  • Km 33 - 40 (Tubac - Chavez Rd): 1979
  • Km 40 - 51 (Chavez Rd - Canoa Ranch): 1977
  • Km 51 - 69 (South of Canoa Ranch - Duval Mine Rd): 1976
  • Km 69 - 75 (Duval Mine Rd - Sahuarita Rd): 1972
  • Km 75 - 80 (Sahuarita Rd - Pima Mine Rd): 1971
  • Km 80 - 95 (Pima Mine Rd - Valencia Rd): 1969
  • Km 95 - 102 (Valencia Road - Interstate 10): 1965

There is one business loop on Interstate 19, in Nogales (former US 89). The former Business Loop in Tucson, travelling down to Sahuarita, was decommissioned in 2004.

Interstate 19 Arizona Guides

Business Loop Interstate 19

Business Loop I-19, Nogales
Looking north on Business I-19 (Grand Avenue) at the intersection with Crawford Street. Through downtown Nogales, Business Loop I-19 follows a couplet with Arroyo Boulevard (south) and Grand Avenue (north). Crawford Street connects the southern end of Interstate 19 (which is only a couple blocks north of here) with the international border crossing (which is a couple blocks south via southbound Arroyo Boulevard). The southern end of Interstate 19 is only a few blocks north of this intersection. Business Loop I-19 begins at the International Border, and joins Interstate 19 at Exit 8, about five miles north of town. 05/24/03
Business Loop I-19 passes through the heart of Nogales, complete with typical chain stores as well as local stores. 05/24/03
Northbound Business Loop I-19 at Junction Eastbound SR 82 in Nogales. In this semi-interchange, motorists must make a left from the business loop onto SR 82, then turn around on a 270-degree arc to cross a bridge over the business loop. SR 82 heads northeast to Patagonia and Sonoita, then joins SR 80 near Tombstone. 05/24/03

Photo Credits:

05/24/03 by AARoads

Connect with:
Interstate 10
State Route 86
State Route 389

Page Updated 03-15-2009.

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