Most Complete Freeway System

[NE2]

Phoenix also had a route running west from the curve on I-17 around Durango Street cancelled - see https://www.arizonaroads.com/urban/.

That was built farther north as I-10.

[Revive 755]

Phoenix also had a route running west from the curve on I-17 around Durango Street cancelled - see https://www.arizonaroads.com/urban/.

That was built farther north as I-10.

Looks more like I-10 was shifted north to the "Southern East-West Freeway" corridor.  There's another document out there, "City of Phoenix Then And Now Transportation" which has a better map showing both freeways.

[roadfro]

What about Las Vegas? I've always been curious to know about planned freeways there. The beltway has incomplete sections. Anything else?

Las Vegas is pretty much complete with anything that has been formally planned.

The 215 beltway still has a couple sections that are still expressway and not full freeway: [1] The northern US 95 interchange, and [2] northern leg between N 5th St & I-15 (a project to convert this segment, except the I-15 interchange, began in July 2018). Keep in mind that an eastern beltway leg was never formally planned as part of the original beltway, and a feasibility study rejected the concept later on.

There has been a outer north beltway (Sheep Mountain Parkway?) concept proposed for the Las Vegas Valley. Given northward growth has slowed down significantly, I'm not sure that is still alive. I also don't know whether the concept ever made it to any formal planning documents.

[US 89]

For my nominations of most complete:

* Salt Lake City (1 cancellation - kind of a southeasterly corridor from the downtown area to I-215)

What was this? I've never heard of this before. I assume it would have roughly followed Foothill? It would be nice, too: rush hour traffic is brutal on Foothill and 13th East.

Other than this, the only NIMBY issues Utah ever truly ran into involved the southeastern quadrant of I-215. Originally, it would have run northeast from the I-15 junction, reaching the base of the mountains at 3900 South. The preferred alternative was moved to the modern alignment a few years later, but then there was a long series of NIMBY lawsuits. Alignments that followed 7200 South and 9000 South were considered, in addition to the no-build alternative, before settling on the current route.

Of course, Legacy Parkway ran into significant problems, but those were more environmentalist than NIMBY related. And it still got built, though as a watered-down parkway with a reduced speed limit and truck restriction.

Salt Lake as a whole still doesn't have enough freeways, but unlike other cities, that's because they weren't planned. Nobody anticipated the level of growth that has occurred, and as a result, Bangerter is still an expressway, there's no east-west freeway in the south valley...I could go on.

[inkyatari]

There has been a outer north beltway (Sheep Mountain Parkway?) concept proposed for the Las Vegas Valley. Given northward growth has slowed down significantly, I'm not sure that is still alive. I also don't know whether the concept ever made it to any formal planning documents.

Yup, Sheep MOuntain Parkway.  I( just did some googling on this because I was curious.  Looks like the BLM did some resource assessment in 2013 on the west leg.  I highly doubt this will ever go anywhere now, because of the creation of Tule Springs National Monument in the area of the proposed path, just a few years ago.