Because cartographers had already been using aerial imagery for decades, the advent of space imaging did not revise our map of the world’s shorelines and land masses very much. World War II had demonstrated the importance of knowing the geography of parts of the earth far from our normal national interests, and the US and its allies invested in worldwide mapping during the Cold War decades. (So, we later learned, did the Soviets.) By the late 1960s, we were even able to use airborne radar imaging to map cloud-shrouded tropical areas.

Early spaceflights demonstrated the value of imagery acquired from space, but it took a few years to clear bureaucratic obstacles and create the Landsat program, which finally launched the Earth Resources Technology Satellite (now often called Landsat 1) in 1972. Once satellite imaging became possible, the new imagery did finally allow us to accurately map the Arctic and Antarctic regions, where even airplane overflights were dangerous, weather-dependent, and of limited utility. In addition, there were places in the remote Pacific that tiny islands erroneously reported by early explorers could definitively be proven not to exist, and taken off the map. One of the few exceptions outside the polar regions of finding new land was Landsat Island, a tiny (25-by-45-meter) island off Labrador.

Curiously, satellite imagery proved more valuable in geomorphology, revealing faults and other structures of the earth’s crusts in ways we could not see from aerial photos covering small areas. And of course the ability to cost-effectively gather imagery in nonvisible wavelengths over large areas transformed crop forecasting and natural resources planning.

Sources: John Noble Wilford's The Mapmakers is a concise (one volume) history of mapmaking, and includes a chapter on space imagery. You may also be interested in the History of Cartography project’s volume on Twentieth Century cartography