IIRC, in the past when new U.S.-China route authorities were established, only CO applied for routes in/out of EWR. CO was certainly the only U.S. carrier that won applications for routes out of NYC area.

Over the years, UA gradually got routes from SFO, ORD, and IAD. The SFO-PVG route award around 1999-2000 was particularly contentious. DL concentrated on ATL. NW's focus was on DTW, and AA's on ORD and DFW. Who can ever forget AA's disastrous application for DFW-PEK in 2006/07. AA pilots publicly said that they would refuse to fly the route should AA win, so the application was amended to become DFW-ORD-PEK. Ultimately, UA won with the "capital to capital" slogan for IAD-PEK.