Interstate 19 connects Nogales and Mexico with I-10 and Tuscon in southern Arizona. 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 State Route 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 SR 86 with I-10 at South Tucson.
Costing $54.2 million, the Ajo Way Traffic Interchange project got underway in March 2016. Completed in Spring 2018, Phase I rebuilt the six-ramp parclo exchange with SR 86 and Ajo Way into a single point urban interchange (SPUI). Additional work added sound walls along I-19 from Ajo Way south to the Michigan Avenue pedestrian bridge. Started in July 2018, Phase II of the project expands southbound I-19 and constructs a braided ramp system between the Irvington Road off-ramp (Exit 98) and Ajo Way entrance ramp. Work on I-19 northbound adds an auxiliary lane from Irvington Road to SR 86 (Exit 99), sound walls, and a new pedestrian bridge at Michigan Avenue. Project II will take 18 months to complete and costs $29 million.4
High Priority Corridor
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 route 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 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 SR 86 / Ajo Way (Exit 99) and Interstate 10 (Exit 101) as part of the Interstate 10/19 Crossing interchange project. Signs installed during the project in 2004 used English units, while other replacements made since and further south retained the metric system. Vocal opposition from area business owners countered efforts from the Arizona Department of Transportation to switch all of I-19 over to English units.2
Commencing in June 2002, a $54.3-million project replaced the substandard trumpet interchange joining I-19 with Interstate 10 in Tucson. Designed with longer ramps as well as improved geometry, the three level interchange at The Crossing was built slightly west of the original exchange.5 Work added ten bridges and eight ramps and reconstructed I-10 between 22nd Avenue and 10th Avenue and I-19 south to Ajo Way / SR 86. 12th Avenue was also rebuilt between 29th and 38th Streets and ramps from I-10 to 22nd Street were combined with new ones at 29th Street.6 Ramps were also added between I-19 and Silverlake Road.
Concrete columns supporting flyovers at the exchange, including the 60 foot high span from I-10 west to I-19 south, are decorated with maize and sunflowers. Painted tan, green and gold, the artwork represents the maize once grown by the Tohono O’odham tribe near the interchange location. The design was approved following a series of public meetings where different options were presented.7 The Crossings project was formally complete with a dedication ceremony held on August 7, 2004.8
North End – Tucson, AZ
South End – Nogales, AZ
Branch Routes – 0
Mileage – 63.35
Cities – Nogales, Tucson
- Junctions –
Source: December 31, 2018 Interstate Route Log and Finders List
I-19 Annual Average Daily Traffic (AADT)
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
Suburban frontage lines both sides of Interstate 19 from Irvington Road north to the SPUI (Exit 99) with Ajo Way and SR 86. The freeway proceeds north along side the Santa Cruz River to I-10 and Silverlake Road. Photos taken 04/26/17.
I-19 northbound defaults onto I-10 west toward Phoenix beyond the departure of Exits 101 and 102. I-10 angles southeast from South Tucson to Davis-Monthan A.F.B. while a frontage road north connects I-19 with 29th and 22nd Streets nearby. Photos taken 04/26/17.
I-10 leading 5.5 miles southeast from Prince Road to Downtown Tuscon and 29th Street, just north of Interstate 19, was widened from six to eight lanes during a $200.3 million project. Ground breaking for work to rebuild the 1950s-built freeway, exit ramps and the frontage road system took place on December 14, 2006. Construction ran from January 3, 2007 to the end of August 2009.9,10,11 Photos taken 04/26/17.
North End Throwback
Button copy guide sign posted for Interstate 19 south, prior to The Crossing project rebuild. This stretch of I-10 was heavily traveled with over 150,000 vehicles per day recorded at the time. Photo taken by Eric Harkness (07/01).
South End – Nogales, Arizona
South at / West Street
Crawford Street takes Business Loop I-19 two blocks east from Sonoita Avenue to Arroyo Boulevard / Grand Boulevard (old U.S. 89). The International Border crossing is located just to the south. Mexico Federal Highway 15 connects Nogales, Sonora with the provincial capital of Hermosillo. The highway continues southward all the way to Mexico City, some 1,350 miles to the southeast. Photo taken 04/26/17.
/ Compound Street west at
- “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. Page originally accessed on April 21, 2017.
- “Construction set for new I-10, I-19 interchange.” Green Valley News & Sun (AZ), April 17, 2002.
- “I-10/I-19 interchange construction to begin.” Green Valley News & Sun (AZ), June 25, 2002.
- “1-10/1-19 interchange – Massive bridge is beginning to reveal its tri-level profile.” Green Valley News & Sun (AZ), January 30, 2003.
- “I-10/I-19 work’s end cause for celebration.” Arizona Daily Star, The (Tucson, AZ), August 3, 2004.
- “Work begins on I-10 improvement project.” Arizona Daily Star, The (Tucson, AZ), December 20, 2006.
- “Prince-to-29th I-10 project gets its symbolic start.” Arizona Daily Star, The (Tucson, AZ), December 15, 2006.
- “I-10 work nearly done, months early.” Arizona Daily Star, The (Tucson, AZ), August 3, 2009.
- “New I-10 lanes about to open: Milestone at The Crossing.” Arizona Daily Star, The (Tucson, AZ), August 16, 2003.
Page updated August 21, 2019.