Greensboro, North Carolina is 2.7 times larger than San Francisco.
Area: 326 km2 calculated
Greensboro is a city in the U.S. state of North Carolina. It is the third-largest city by population in North Carolina and the largest city in Guilford County and the surrounding Piedmont Triad metropolitan region. According to the 2012 U.S. Census Estimate, Greensboro's population is 277,080. Wikipedia
Area: 122 km2 calculated
San Francisco, officially the City and County of San Francisco, is the cultural center and a leading financial hub of the San Francisco Bay Area and Northern California. Wikipedia