Southwest, Alaska Add 17 Nonstop Routes at San Diego Airport

Alaska Airlines and Southwest Airlines are expanding aggressively at San Diego International Airport, rolling out 17 new nonstop routes for 2026 and 2027, according to Simple Flying, which cited Cirium Diio schedule data. Several of the routes have already begun flying, and the buildout marks one of the sharpest capacity jumps either carrier has made at the airport.

Simple Flying reported that Alaska's seat count for sale at SAN in 2026 has reached 8.4 million round-trip seats, a 35% jump over the carrier's previous high set in 2025. Southwest's tally is even larger at 13.3 million seats, up 20% year-over-year. Combined, the two airlines have added 4.4 million seats to and from San Diego this year alone. The report framed the buildup partly as a competitive response between the two carriers, each pushing to outgrow the other at the airport.

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Loreto returns after two decades without nonstop service

Among the additions, Alaska's new route to Loreto in Mexico's Baja California stands out for its history. Department of Transportation data cited by Simple Flying shows nonstop flights between SAN and Loreto last existed in 2006, operated by Aeromexico using the McDonnell Douglas MD-87, a service that ran from 2002 and filled just 61.1% of its seats on average. Alaska is starting far smaller: two weekly winter flights on a 76-seat Embraer E175 under its Horizon Air regional brand. The airline is also betting on the route's connecting value through San Diego, including onward links that once ran to San Francisco, where Alaska ended its own Loreto service in April 2026.

Other new markets fill gaps that regional and now-defunct carriers left behind. Tulsa, Oklahoma gets daily Horizon Air E175 service starting March 18, 2026 — a city not served nonstop from San Diego since Frontier pulled out in 2018, and before that Expressjet in 2007 and 2008. Santa Barbara returns to Alaska's map on April 21, 2026 with two daily flights split between Horizon Air and SkyWest-operated E175s; Southwest already flies the route, and Alaska itself last served it in 2021 and 2022.

Dallas and Oakland get mainline competition

Alaska is also adding mainline competition on two larger routes launching the same day, April 22, 2026. Dallas/Fort Worth gets two daily flights using a mix of 737-800, 737-900ER and 737 MAX 9 aircraft, joining American and Frontier on the route. Oakland gets four daily E175 flights via Horizon Air and SkyWest, stepping into a market Spirit Airlines abandoned in 2025 before the carrier's collapse, and going head-to-head with Southwest, which already serves the pair.

Simple Flying's report did not detail the remaining routes among the 17 announced, though it noted more are set to launch through 2027. Whether the combined capacity surge at SAN holds up remains an open question the outlet raised directly, given how quickly both airlines have layered in seats. Travelers eyeing the newer markets, especially seasonal ones like Loreto, should confirm days of operation before booking, since some of the added flights run only a few times a week.