United Airlines has continued to expand its domestic and international network from its major hubs, including San Francisco International Airport (SFO), its fifth-busiest hub. This year, the Star Alliance member is operating the largest summer schedule in its history from San Francisco. From October 25, United is reinstating daily flights between San Francisco and Cincinnati Northern Kentucky International Airport (CVG). Related United Airlines Launches 4 New Nonstop Routes From Major Hub: See Flights Now All of them were served before, but they'll now have five daily flights between them. Domestically, United offers flights from San Francisco to most of the major US markets, including New York, Chicago, Boston, Houston, and Las Vegas.