Interstate 19 is a short route in southern Arizona that connects Interstate 10 and Tucson with Nogales and Mexico. The freeway curves west around Crawford Hill from Grand Avenue (old U.S. 89) and the international border to bypass Downtown Nogales north to Arizona 189. North from Rio Rico, I-19 parallels the Santa Cruz River to Tubac, Green Valley and the south suburbs of Tucson. The lone six lane section joins Arizona 86 with Interstate 10 at South Tucson.
With the establishment of Intertate 14, I-19 is now the fourth shortest two-digit route within the Interstate system, ranking above I-2 and I-97.
A $54.2 million, 23-month project started in March 2016 replaces the six-ramp parco interchange with Arizona 86 and Ajo Way with a single point urban interchange (SPUI). Additional work adds sound walls along Interstate 19 from Ajo Way south to the Michigan Avenue pedestrian bridge. Project II will expand southbound Intertate 19 and construct a braided ramp where the Irvington Road off-ramp (Exit 98) passes over the new on-ramp from Ajo Way. An auxiliary lane will be added northbound from Irvington Road to Arizona 86 (Exit 99), and sound walls will be erected south from a replacement Michigan Avenue pedestrian bridge. Project II will take 18 months to complete and costs $29 million.4
High Priority Corridor
The section of Interstate 19 from Nogales to Tucson is part of High Priority Corridor 26: CANAMEX Corridor.
Parallel U.S. Routes
Interstate 19 ultimately replaced the original routing of U.S. 89. Some old segments of U.S. 89 at Tucson and Nogales were incorporated into Business Loops for I-19. The Tuscon business route was eventually decommissioned.
Interstate 19 opened initially from Rico Rico Drive (Exit 17) to Palo Parado Road (Exit 25) in 1966. The freeway was completed in 1979 when the section from Tubac (Exit 34) to Chavez Road (Exit 40) opened to traffic. See the I-19 Arizona guide for the rest of the time line.
One of the unique features of Interstate 19 is that most of the exit numbers and distance signs are based on the metric system, a first for the U.S. Interstate system. The use of metric units along I-19 was the result of a President Carter administration pilot project aimed to have the United States adopt the system. The metric units also served as a hospitality measure for Mexican tourists headed north to Tuscon and Phoenix.
Some of these metric signs were replaced between Arizona 86 / Ajo Way (Exit 99) and Interstate 10 (Exit 101) as part of the Interstate 10/19 Crossing interchange project. The 2004-installed signs use English units, while other replacements made since and further south retain the metric system. Vocal opposition from area business owners have countered efforts from the Arizona Department of Transportation to switch over to English units.2
A $54.3-million in construction upgraded the substandard trumpet interchange at Interstate 10. Commencing in June 2002, “The Crossing” rebuilt the former trumpet interchange with new high-speed ramps and added connections to nearby 12th Avenue for I-10 and 29th Street / Silverlake Road for I-19. Work was completed as part an overall Interstate 10 rehabilitation through the Tucson metropolitan area. A dedication ceremony held on August 7, 2004 marked the project completion.3
North End – Tucson, AZ
South End – Nogales, AZ
Branch Routes – 0
Mileage – 63.35
Cities – Nogales, Tucson
- Junctions –
Source: December 31, 2017 Interstate Route Log and Finders List
I-19 Annual Average Daily Traffic (AADT)
|Location||Vehicles per day|
Source: 2001 Arizona Interstate Annual Average Daily Traffic (AZDOT)
Initial portions of I-19 ran south from I-10 to Valencia Road (Exit 95) by 1965 and between Mariposa Avenue (Exit 4) and Palo Parado Road (Exit 25) by 1968.
U.S. 89, truncated south of Flagstaff as approved by AASHTO on June 15, 1992, was designated as Business Loop I-10 north of I-19 and as Business Loop I-19 south of I-10. The I-10 business loop was eventually decommissioned by the late 1990s.
North End – Tucson, Arizona
South End – Nogales, Arizona
- “Some I-19 metric signs going,” Tucson Arizona Daily Star, January 19, 2004.
- “Arizona highway signs in metric units may change.” The Arizona Republic, October 5, 2014.
- Building the I-10/I-19 Traffic Interchange,
http://www.1019crossing.comArizona Department of Transportation project web site.
- Southcentral Districts Projects – Interstate 19: Ajo Way Traffic Interchange. Arizona DOT project web site. Accessed April 21, 2017.
Page updated April 21, 2017.