I got my information on Phoenix from the Wikipedia section on market share, I didn't make it up:
Airline market share
Top airlines at PHX
(December 2022 - November 2023)
Rank Airline Passengers Percent of market share
1 American Airlines 15,301,000 34.34%
2 Southwest Airlines 15,004,000 33.67%
3 Delta Air Lines 3,333,000 7.48%
4 United Airlines 2,562,000 5.75%
5 Frontier Airlines 2,480,000 5.56%
6 Others 5,881,000 13.20%
https://en.wikipedia.org/wiki/Phoeni...Annual_traffic
And I certainly didn't mean to say they don't have major operations there, they obviously are well connected regionally. I just mean compared to how many of AA's other hubs are comprised, PHX is a bit of an outlier. Yes the lack of international is the main one (London is the sole transcontinental airport), but also it's relative closeness to DFW, which is such a behemoth and is a main east-west connector. Other hubs share traffic with other big full service carriers (ie. LAX, JFK, ORD) because of their sheer size and market importance, which can handle multiple legacy carriers hubs, but usually airports do not come that close with a "low cost" domestic carrier like Southwest almost beating them.