Endpoints of the current and historic
highways "US 89A" (or "Alternate US 89")

Historically, one could continue south of Flagstaff AZ on US 89, using one of two options. Alternate US 89 went south through Sedona and Cottonwood to Prescott. US 89 was signed westward with US 66 through Williams to Ash Fork, and then south through Chino Valley to Prescott. There, it met US 89A and continued southward. Between Wickenburg and Phoenix, US 89 was co-signed with US 60/US 70. And the road from Phoenix to Florence Junction was signed US 60/70/80/89. There, US 60/70 separated and headed to Globe, but US 80 and 89 remained together all the way to Tucson. From there, US 89 continued due south to the Mexico border at Nogales. The photo below shows the historic end of Alt US 89 in Flagstaff:

Jensen, Sep. 2002

That was looking north on Milton Road (or Alt AZ 89), where it joins old US 66/89 (which is now signed Business I-40). This was the north end of Alt US 89. However, the US 89 sign is no longer correct; it's now Alt AZ 89 ahead - and that designation actually ends where US 89 begins. That sign has since been changed, and it's more accurate now with respect to US 89 signage...

Elbert, Apr. 2008

...however, it's actually Business 40 to the left (not I-40).

The south end of US 89A was just outside Prescott AZ (locals pronounce it "PRESS-cut"). Today there is an AZ hwy. 89A, but in 2001 the Prescott end was re-routed such that its current terminus is not located at the same place as historic US 89A:

Jensen, Sep. 2002

That's looking west at the modern south end of AZ 89A (or Prescott-Jerome Highway). The crossroad is AZ 89 (old US 89): downtown Prescott is about 8 miles to the left, and the airport is just to the right. Straight ahead is a local arterial called Pioneer Parkway. The south end of historic US 89A was about 2 miles south (left) from here; it intersected 89 at an area known as Granite Dells. Below is the old terminus:

Jensen, Sep. 2002

Jeff reports that this road is not marked with a street sign or anything, and it is closed off at an old bridge not far behind the camera. But the signage posted across from its intersection with AZ 89 (historic US 89) is a dead giveaway that this road used to serve in a much more important capacity (I'm glad Jeff photographed it when he did; I wouldn't be surprised if these signs were removed in the future). This was the south end of US 89A. The green sign points left to Prescott (even though this road is actually within Prescott city limits now) and right to Ash Fork.

US 89 has another alternate route - one which exists to this day. Alt US 89 thorugh Arizona (plus the three miles worth in Utah) used to be mainline US 89, until the Glen Canyon Bridge was built in Page. The photo below is looking west on northbound US 89 in Kanab UT:

Hamilton, July 2004

Both directions used to be mainline US 89. Below we're looking southbound on US 89:

Field, Oct. 2003

Modern US 89 continues to the left. Straight ahead is old US 89, later Alt US 89, but note that UDoT now considers that road to be U-11. The reassurance marker ahead looks like this:

Hamilton, July 2004

Three miles ahead, U-11 ends...

Hamilton, July 2004

...and the stateline marks the current north beginning of Alt US 89:

Hamilton, July 2004

About 90 miles ahead, that highway ends where it reconnects with mainline US 89 at Bitter Springs AZ:

Hamilton, July 2004

The photo below was also taken at that junction; this is looking south on US 89 at the junction with Alt 89:

Field, Oct. 2003

Heading the opposite direction, the south beginning of Alt US 89 looks like this:

Hamilton, July 2004

If you take that turn, you'll soon see the first northbound reassurance marker:

Hamilton, July 2004

At the Utah line, the route ends and becomes U-11...

Hamilton, July 2004

...and three miles ahead in Kanab is the historic north end at US 89:

Hamilton, July 2004

My main US 89 page can be found here.