American Airlines is holding firm in their commitment to further the evolution of how and where the carrier’s tickets are shopped and sold. As I previously blogged, American is seeking to reduce distribution costs by steering away from the legacy global distribution system (GDS) model used by most online travel agencies (OTAs). New signs are emerging that show American is beginning to make headway in this battle.

Earlier this week, Priceline signed an agreement with American stating they will use the Direct Connect technology in the near future. The negotiations for this contract have likely been going on for some time given American’s ads directing traffic to Priceline (and Kayak). Also this week, American outted Vegas.com as being contracted to use the direct link, and it is being reported they’ve been using it for about five months already. Separately, US Airways and Expedia signed a good faith type of agreement whereby the carrier’s flights and ancillary services will continue to be offered exclusively through GDSs.

This led me to look at just how much traffic is steered to the OTAs, and I was able to find a recent summary revealing the most popular travel shopping websites in the United States for the week of January 15, 2011.

While the actual number of visits isn’t revealed by website, it is still interesting to see how the “big four†(Expedia, Priceline, Travelocity, and Orbitz) compare against each other. The spread between number one Expedia and number two Priceline is significant, and allows the former to maintain its majority share consistently week to week. Also, the previous period’s results showed Orbitz & Travelocity switched in positions, so I bet that is a constant week-to-week occurrence.

I’ll be keeping my eye on these figures in the coming months, and likely post any major moves I notice.