Phoenix-Tucson I-10 Super Corridor

[Keith Meyer]

Could continued strong population influx into Arizona cause Phoenix and Tucson to merge into a common mega-region one day? This article suggests that current trends make this a possibility. The core areas of Phoenix and Tucson are separated by 120 miles. As a point of comparison, Dallas and Fort Worth are about 30 miles apart. 

https://www.orionprop.com/topfive/could-population-growth-propel-phoenix-and-tucson-to-merge/

I think this is an interesting concept. Living in San Diego currently and seeing the population outflow from California due to severely off-balance Home Affordability indices and a growing reputation as an state unfriendly to business growth, I don't think that the current trends are going to be slowing down any time soon. It looks like there are several high-speed rail projects currently under planning in this region in Arizona which would also increase the feasibility. 

Could other areas with massive recent population influx like Denver-Colorado Springs explore a similar possibility?

[Dan H.]

They seem far apart compared to other dual cities like Dallas/Fort Worth, Minneapolis/St Paul, Fargo/Moorehead, etc.  I suspect eventually it could happen but I would suspect it is probably decades from happening.   However, unlike So Cal were military bases can provide clean delineation of city boundaries (Pendleton for example), for Phoenix/Tucson there is mostly only desert separating them (many miles of harsh desert).

BTW CA population continues to increase.  People are moving in a little faster (percentage wise) than people moving out.  In terms of number of people (not percentage) it is a large net increase (just over 2.5M this decade - last I looked that was 2nd highest (only behind Texas)).  To put it into perspective, that increase is more than the entire population of around 17 states.  In terms of percentage Ca is growing at a moderate rate but in terms of actual increase, its population has increased a lot.  This information, on a city level, is some of the metrics I use to determine the expected RE market growth.