Nevertheless, LAX is #2, Miami #3 and Chicago #4. The new AA must be very happy with its current strategy. They have hubs in 50% of the top 10 cities, including the top 4. And from that perspective, UA has hubs in 4 of the 5 largest O/D markets. DL loses that game, as its mega-hub in ATL is #13; SEA #14, MSP #17. SLC? #25, the last one on the list.
And yet...DL is having record profits while UA stumbles repeatedly and loses $$. It's not all about O/D at the end of the day, clearly.
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Below is a list of the largest origin and destination airports in the US. This list does NOT include connecting traffic, only traffic originating for or destined to the airport(s) in question. The list includes international and domestic traffic. The list is for all airports in a metro area (ex. JFK, LGA, EWR, HPN for NYC/LAX, BUR, ONT, SNA for Los Angeles). The source of the data is the DOT annual report plus MDIT data. The data is listed in number of passengers per day. Top 25 markets are listed:
1) New York: 245,750 passengers per day
2) Los Angeles: 184,296
3)
I don't want to sound like a stickler for detail

but remember that list is a list
per market not
per airport. Comparing just one airport against another, LAX has the largest O&D traffic of all airports.