USC's not the greatest university, but it has some decent programs. Before international business studies recently became trendy at some well and not so respected universities and before Thunderbird first began tossing out global MBA degrees (now legit, then dubious), USC was an old university. The strong reputation of its' global programs is less of a mystery than first meets the eye, including for the eyes of a fair number of people outside the southeast and mid-Atlantic states.
History, including pre- and post-Civil War, involved and forced Palmetto State trading of a lot of things with other nations, forced accessing financing from alternative sources, and eventually evolved over a much longer time to starting internationally-focused research, global partnerships, programs, etc. Getting a head start continues to benefit USC's well-respected undergraduate and graduate business program reputations.