In its posters for New York, the eastern point on its transcontinental "Main Line", United often returned to Central Park as a theme, far more so than any other airline. In one of the airline's earliest series, the famous southeast corner and its pond is the focal point, looking toward some of the famous hotels that rise over the park.
Joe Feher was a Hawaii-based artist who painted numerous pictures of his home soon-to-be state, including two stunning posters for United that are part of this same series. He also painted a wide series of watercolors from all over the country that were distributed as prints by United and included in calendars in the 1950s.
Every poster in this series -- others advertise Southern California, San Francisco, Yosemite, the Pacific Northwest, Colorado, Chicago, and New England -- is, in a word, amazing. They are also quite valuable. Feher hid his signature in most of his works, making them hard to find. I have yet to find the signature in this piece, but I have no doubt from the style and its place in the series that this is his work.