United often has bolder moves than some of its staid American cousins. Its foray into South America, long the backyard of American Airlines, and Pan Am and Eastern before it, is one such example. Although UAL couldn't make the extension to Montevideo last, the carrier still does the nightly runs to Sao Paulo and Buenos Aires, as well as Rio de Janeiro, which is, somewhat bizarrely, not even featured on this map.
United's mighty Brazilian bond within the Star Alliance, first to the now-fallen VARIG, whose connecting options from Guarlhos are shown above, and newly-ascendant TAM, certainly contributes to the success of the venture. Brazil's ascent as the second economic giant of the Western Hemisphere hasn't hurt, either. Note the Mapquest logo in the corner-- this was the era of web 1.0.