If you live in San Diego, you are a happy camper right now. Alaska and Southwest both continue to aggressively add new flights as they look to get a leg up as the most important airline in the market. The opening of the new Terminal 1 has been an absolute boon for the constrained airport, and now Southwest has fired its latest volley in this battle.

Southwest extended its schedule from early Aug through the end of Sep last week. All of these new additions start Aug 4:

• Portland (OR): 1x to 2x daily (Alaska has 5x daily)
• Salt Lake City: 1x to 2x daily (Alaska has 3x daily, Delta has 5x daily)
• Santa Barbara: new 1x daily (Alaska has 2x daily)
• Seattle: 1x to 2x daily (Alaska has 10x daily, Delta has 5x daily)

I know what you’re thinking. This looks like a message toward Delta as well as Alaska, right? I don’t think so. Santa Barbara is new and overlapping Alaska’s recent additions. Those other three? Those are the only markets (save Fresno) where Southwest has at least 1x daily fewer flights than Alaska.

Combined with the non-San Diego additions where Southwest matched the recent Alaska Burbank – Honolulu flight and added Ontario – Honolulu — a market only Alaska/Hawaiian flies — this is clearly a move targeting Alaska’s efforts in the southern half of the state.

All of this looks like an airline setting boundaries. In the LA Basin, Southwest seems to be saying that even if Honolulu is a Hawaiian hub, Southwest owns the secondary airports surrounding LA. In San Diego, it’s somewhat more complex.

Alaska/Southwest San Diego Overlap Markets – Aug 2026

^{Maps generated by the Great Circle Mapper – copyright © Karl L. Swartz.}

When we look at a map of overlapping markets above, we can see some trends. (And yes, I have left off both Anchorage, which is served only by Alaska, and the Hawaiian Islands where both fly to Honolulu and Kahului while Alaska alone flies to Līhuʻe and Kona.)

The two biggest overlap regions are intra-California (including Vegas and Phoenix, which behave the same) and mid- to large-markets in the Pacific Northwest. Sure, there are stragglers, but those are by far the two largest chunks. Southwest flies these with aircraft that have at least 143 seats while Alaska uses its 76-seat Embraer 175s. Alaska has a more premium-heavy configuration and can do more frequency in smaller markets. Southwest can keep its unit costs lower, but it has a more basic product. Both can work.

Where this gets interesting is when we look at where the airlines don’t overlap.

Alaska/Southwest San Diego Markets Without Overlap – Aug 2026

^{Maps generated by the Great Circle Mapper – copyright © Karl L. Swartz.}

These airlines clearly have their own domains. For Southwest, it has staked its claim on east-west flying from the Rockies to, well, I dunno, call it the Rust Belt. This is a midcon strategy, and if we ignore serving different airports in Chicago, the only market Alaska serves that Southwest doesn’t is the newly-added Tulsa run.

As for Alaska, it has two areas of focus. It stretches into smaller north-south markets which it is uniquely positioned to do thanks to the those 76-seaters. It also presses mainline into service on transcon runs.

It seems that Southwest is setting boundaries based on the fleet it has, but that doesn’t stop the airline from firing some warning shots if boundaries are crossed. The Santa Barbara flight gives a sense of just how small a market can be before Southwest will step in. Alaska always runs the risk of having too much success in a market which results in Southwest stepping in. This already happened with Fresno this year, and next year Southwest is already going into Santa Rosa before the Santa Barbara flight starts.

Southwest also seems content competing with Alaska up and down the West Coast in larger markets, realizing it needs to up frequencies where it has too few in order to compete. Those just happen to be in Alaska’s biggest hubs (and Salt Lake). And it too sends the message loud and clear that Southwest isn’t afraid of Alaska even in hub-to-hub markets.

By next August, Southwest will have more than 1,000 monthly flights more from San Diego than any other California airport. And while San Diego keeps growing, others have shrunk.

Top 5 Southwest California Markets by Seats by Month

^{Data via Cirium}

I struggled with a good way to display this chart, because I realize it is a jumbled mess. But these are the current top 5 markets for Southwest in California by seats. For years, LAX was the largest, but both Oakland and San Diego grew quickly, as did San Jose from a later starting point. Those five were all pretty close together going into the pandemic.

Coming out of the pandemic? Oakland was still number one, but San Diego and Oakland have gone in very different directions since then. If this schedule holds, Oakland will have less than 60 percent of the seats that San Diego has at the tail end of next summer. Even worse, it has dropped to fifth place in the state for the airline.

Meanwhile, Sacramento was down low throughout this entire time, but it has held up better than most of the rest. It’s now the second largest market in California for Southwest. LAX and San Jose both fell hard after the pandemic, though LAX fell hardest and earliest. Now, thanks to recent adds, LAX is back in a distant third place.

All this is to say that San Diego is by far the airline’s most important priority in the state. You might say the same for Alaska. And so, it’s time to fight.