Last November, a standoff between two major airlines and the Department of Justice was settled, and the airline merger moved forward. A core part of the settlement was a requirement that the new American Airlines Group (AAL 1.41%) divest 104 slots at Washington National Airport. Now, we have the results of some of the slot divestments, and know the names of the airlines that increased their presence at this highly valued airport.

Location, location, location
Although Washington, D.C. has three major airports serving the district, Washington National Airport has one key advantage over Washington Dulles International and Baltimore-Washington International: It sits right next to the heart of the district, whereas both of the other major airports sit at least 20 miles away. This prime location makes flights into Washington National particularly appealing for business travelers and politicians who are often willing to pay a premium for the increased convenience.

However, due to the airport's size and passenger demand, slots at the airport are tightly held and quite valuable for airlines targeting higher-paying flyers. With this in mind, it's no surprise that rival airlines were eager to acquire the slots that American Airlines Group is being forced to divest.

As expected, both Southwest Airlines (LUV 1.83%) and JetBlue Airways (JBLU 1.41%) acquired slots to expand their presences at the airport. The current numbers show that Southwest and JetBlue got 54 slots and 24 slots, respectively. In addition, JetBlue now owns 16 slots previously leased from American Airlines.

The expansion by JetBlue is key to the airline's strategy. With a strong northeast presence, JetBlue was finding expansion at popular airports difficult in a system where major carriers retain the best real estate. The slots at Washington National give JetBlue not only an expansion opportunity, but also connect more of its network with a prime location. Investors should be on the lookout for additional expansion by JetBlue, and pay attention to what the airline does with the Washington National slots.

Southwest Airlines is also eager to expand into prime markets. For much of its history, Southwest has operated much of its network through less popular airports. While this helps the airline to save on airport fees and frequently avoid competition, the lack of network presence at popular airports hampers Southwest's efforts to attract business travelers. Through the purchase of these Washington National slots, Southwest has boosted the presence of its network. Airline investors should continue to monitor whether Southwest moves further in its efforts to attract business travelers.

The slot sale also brings a greater presence for a relatively small competitor to Washington National. According to the AP, Virgin America, currently operating one daily flight to San Francisco from Washington National, has confirmed it will now have enough slots for a total of five daily round-trips from the highly popular airport.

Going forward
American Airlines Group has, so far, pretty much got the merger it wanted. Integration is being handled smoothly, financial results are strong, and the airline's shares are up more than 40% since the official merger date on Dec. 9.

Southwest, JetBlue, and Virgin America all come away as winners from this merger. The slots they are getting at Washington National are allowing them to break into an otherwise tightly held market. Look for all three of these airlines to make full use of this prime real estate as they battle for the travel dollars of business travelers and politicians.

Editor's note: A previous version of this article misstated the number of Virgin America's round-trip flights between Reagan National and San Francisco. The Motley fool regrets the error.