It's a question that occasionally pops up on our social media feeds: Why is it called Interstate 17?

And it's not the "17" part they are asking about.

Rather, it's the fact that all 147 miles of highway runs between Phoenix and Flagstaff ... and that's it. How can it be called an "interstate" when it never reaches outside of Arizona? The same question can be asked about Interstate 19, which runs 102 kilometers (63 miles) between Tucson and the international border.

If we went solely off Webster's definition of "interstate," it admittedly doesn't make much sense. But when we talk about interstate in terms of highways, we have to turn to a different criteria. 

According to the Federal Highway Administration, the Federal-Aid Highway Act of 1956, which created the system, called for uniformity in construction standards. These standards were developed by the American Association of State Highway Officials (now the American Association of State Highway and Transportation Officials or AASHTO) and are the benchmark for any highway that wants to be an interstate. The metrics include having controlled access, design speeds of 50 to 70 MPH depending on terrain, a minimum of two travel lanes in each direction, 12-foot lane widths, a 10-foot right shoulder, and a 4-foot left shoulder.

And the criteria for adding another highway to the system is also straightforward: it must meet the interstate standards, be a logical addition or connection, and be coordinated among all jurisidictions it will pass through.

The Federal Highway Administration also has a fantastic page dedicated to debunking myths about the interstate system. There the agency specifically address highways that don't ever leave their state of origin.

"The key," according to the Federal Highway Administration is "each highway must meet Interstate standards, be a logical connection to the interstate system, connect to an existing route or be a congressionally designated future interstate corridor that eventually will connect on at least one end." 

This definition is why you'll see interstates that are beltways around large metropolitan areas or in places such as Hawaii, Alaska and Puerto Rico that cannot connect to other states. It's also why I-17 and I-19 both can be called interstates.

Though they don't go anywhere nearly as far as I-40 or I-15, both I-17 and I-19 have fascinating histories that can give additional insights into these intrastate interstates.

Anyone who’s driven on Interstate 17 near Sunset Point this time of year has witnessed the mystery of a scrub tree in the median suddenly decorated with holiday finery. 

Many refer to it as the Mystery Tree.

For more than 30 years, someone has secretly decorated it in the middle of the night. Like magic, the tree suddenly gleams with ornaments to the delight of those who pass.

How does this happen? Who decorates the tree? Why doesn’t anyone see them?

Perhaps no Arizonan has captured this mystery better than Dolan Ellis, Arizona’s official balladeer for more than 50 years. Ellis might look like a rough and tumble cowboy with his hat, boots and guitar, but this baritone sings from the bottom of his soul.

Ellis named the tree Scrubby and commemorates it in a song of the same name, which he performs in this video produced ADOT's video team.

The first verse:

Out in Arizona there’s a story to be told.
Of Scrubby, the little cedar tree that grows beside the road.
I-17 to Flagstaff, from the desert down below,
And a random act of kindness by some secret, caring soul.

It’s the idea that people care enough to bring joy to others that strikes a chord with Ellis, whose own generous spirit spreads across his face as he sings the song, sharing the joy still further.

It brings a smile to every face that passes by that sight.
Scrubby becomes a rock star, and for him this song I write.

The song is one of hundreds Ellis has written since crossing the Arizona state line with his pregnant wife in 1959. During his storied career he has performed before millions of people and won a Grammy Award while a member of the New Christy Minstrels.

He has sung songs for hundreds of thousands of Arizona schoolchildren and been inducted into the AZ Music and Entertainment Hall of Fame, among many other career highlights.

He has logged countless miles across Arizona in four-wheel drive vehicles and explored every nook and cranny of culture and climate, guitar always at the ready.

Many of his songs are about Arizona highways and the places and sights that have led him into direct contact with the state, its people and its culture. 

Sights like Scrubby.

Scrubby is a cedar tree and no one knew his name.
Till someone decorated him, and gave him pride and fame.

You can learn more about Ellis, his performance schedule, history and songs at DolanEllis.com. You can also learn about the Arizona Folklore Preserve in Ramsey Canyon in the Huachuca Mountains, which Ellis founded to preserve songs celebrating Arizona’s western heritage and culture, at ArizonaFolklore.com.   

Sept. 26 was a big day, both for us and for everyone who drives on Interstate 17 north of the Valley.

As we said in a news release, Governor Doug Ducey, accompanied by ADOT Director John Halikowski, the heads of the state Department of Public Safety and state Office of Tourism, and business leaders, elected officials and transportation stakeholders, announced more than $300 million in improvements coming to the highway between Anthem and the Sunset Point Rest Area. These include adding a third lane in both directions on the 15 miles between Anthem and Black Canyon City and 8 miles of flex lanes on the grade between Black Canyon City and Sunset Point. 

This announcement stemming from state, local and federal partnership, including $130 million proposed in Governor Ducey’s executive budget, came during an event in Anthem, just a stone's throw from where the freeway can see more 50,000 drivers on especially busy days such as the beginning and end of holiday weekends.

As you can see in the slideshow to the right, lingering storm clouds couldn't dampen our enthusiasm for this project, which is scheduled to start in 2021 and be completed in 2023.

You can forgive us if we have Interstate 17 on the brain today. 

With Governor Doug Ducey announcing a slew of improvements to the highway north of the Valley – widening 15 miles between Anthem and Black Canyon City, adding 8 miles of flex lanes north of Black Canyon City, a total of more than $300 million of improvements – we are thinking a lot about this Key Commerce Corridor between Phoenix and northern Arizona.

As you might know, the road was the original State Route 69 and ran between Phoenix and Prescott. Though started in 1936, the Great Depression and World War II delayed the road's dedication until 1952 – and it would not be fully paved until 1955. Soon afterward plans were put in place for another highway, called State Route 79 and starting at the newly christened Cordes Junction, to head through the Verde Valley and all the way up to Flagstaff. After a series of contracts for companies to build 5- or 10-mile stretches, this highway connection between Valley and Flagstaff was in place by September 1961.

After the start of the interstate system, Arizona decided the sections of State Route 69, State Route 79 and the Valley's Black Canyon Freeway would be designated as "Interstate 17." This transformation would be complete in 1978. You can read more about the history of I-17 in our 2011 Arizona Transportation History. 

All this had us finding photos showing what I-17 used to look like. The undated photos here start in north Phoenix near Union Hills and then go down into Camp Verde.

With the announced improvements, plus work underway to repave and rebuild bridge decks between the Coconino County line and I-40, we are making sure this important highway continues to serve Arizona motorists for years to come. 

For those of us looking forward to new lanes being added to Interstate 17 in the Anthem and Black Canyon City region, this week was another important one as ADOT prepares to start construction in less than two years.

The Federal Highway Administration provided great news that Arizona will receive a $90 million Infrastructure for Rebuilding America (INFRA) grant to help fund the big project that will improve I-17 between Anthem Way and Sunset Point Rest Area.

The photo above shows ADOT Director John Halikowski at right, in Washington for a ceremony led by U.S. Secretary of Transportation Elaine L. Chao, who is in the center. 

The $90 million INFRA grant for Arizona was the second-largest among more than $855 million in such grants provided by the Federal Highway Administration. It followed a $125 million grant awarded to Alabama for construction of a new bridge over the Mobile River channel.

The federal grant will help fund the construction of a flex lanes system between Black Canyon City and Sunset Point (more on the flex lanes below) and add third lanes in both directions along 15 miles of I-17 between Anthem Way and Black Canyon City.

This is the latest positive news about available funding for the I-17 improvements north of Phoenix. The budget approved by the state Legislature and signed by Governor Doug Ducey included an investment of $130 million in state funds to allow full construction of the third lanes between Anthem Way and Black Canyon City as part of the larger project.

And here’s a little more information about the I-17 flex lanes, in case you’re not familiar with them. They will be built as a separate two-lane facility next to the existing southbound lanes along the 8 miles between Black Canyon City and Sunset Point. These new lanes will be used to carry one direction of traffic at any one time depending on traffic needs.

For example, northbound traffic will have access to the flex lanes on a Friday or southbound traffic will be able to use the new lanes on a Sunday when a lot of drivers are returning to the Valley. This system also could provide lanes in either direction if an incident were to close the regular I-17 lanes in the area between Black Canyon City and Sunset Point.

Safety is ADOT’s top priority when it comes to the flex lanes. Yes, there will be movable gates at each end to control access. Barrier wall also will separate the flex lanes from the adjacent regular southbound I-17 lanes.

Available funding for the I-17 improvement project will allow construction to start by 2021 and be completed by 2023.

 

Ever see a picture of friend in high school, and they sort of look the same but are also sort of unrecognizable?

That's how we are feeling about this picture taken by the Arizona Highway Department in 1966 and available through the Arizona State Library's digital image collection. Can you pinpoint where this was taken? Take a good long look, we'll give you a minute.

No peeking below. Got it? 

Well, how did you do? 

If you guessed this was a shot of Interstate 17, with Camelback Road closest to the camera, then you are right! Looking south, you also can see interchanges at Indian School and Thomas roads and then beyond. 

If you weren't able to place it right away, don't feel bad. It took some sleuthing on our part and finding that the mobile home park in the foreground still exists to identify this.

If you were to take a similar picture today (or take a screenshot of Google Maps, as the case may be) it might look something like this:

Like we said, sort of the same, but also sort of unrecognizable. But we can all hope that we will look as good in two pictures taken 53 years apart!

 

It's not exactly "Meerkat Manor," but you can see how a photographer could easily think of those African mammals and their habit of standing sentry while looking at the top of the new bridge girders on Interstate 17 at Pinnacle Peak. 

These rebar facsimiles will also quickly disappear as the project to expand Pinnacle Peak over I-17 and rebuilt the interchange continues. You can see a more expansive view of what the girder installation looked like in the photo gallery below.

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Peek with us into the cabin of a crane as an operator removes the forms for new bridge piers on Interstate 17 at Pinnacle Peak Road.

It's a snapshot (literally) of a snapshot (metaphorically) of the work going into the massive project to improve this north Valley interchange by widening I-17 and constructing news interchanges at Pinnacle Peak and Happy Valley Road. You can learn more by visiting our website.

You can also check out more photos of recent construction in the photo gallery below.