The first small planes soon gave way to ever larger craft, spanning ever longer distances. As the 1930's began, Pan Am's small fleet of land planes was complemented by newer, bigger and faster flying boats. Constantly expanding route networks soon spread out from bases in Miami and Brownsville to encircle the Caribbean, and then the whole of Latin America. By mid-decade, the ultimate hurdle was bested, and Pan Am's "Clippers" were crossing the vast Pacific, while Pan Am subsidiary airlines flew in China and Alaska. By the decade's end, the ultimate flying boats, Pan Am's fleet of Boeing B-314s were linking all the continents in the Northern Hemisphere.