"America used to be full of odd beers. In 1873, the country had some four thousand breweries, working in dozens of regional and ethnic styles. Brooklyn alone had nearly fifty... Beer has lagged well behind wine and organic produce in the ongoing reinvention of American cuisine. Yet the change over the past twenty years has been startling. In 1965, the United States had a single craft brewery: Anchor Brewing, in San Francisco. Today, there are nearly fifteen hundred."
This from an excellent New Yorker article about Sam Caglione of Dogfish Head and the rise of craft brewing in America.