What was the first true American beer Style?

Steam beer, the first uniquely American beer style, evolved in the San Francisco area during the 19th century. After prohibition ended, the Anchor Brewing Company was left as the sole producer of steam beer.  The company was near closure in 1965, whereupon Fritz Maytag, great-grandson of the Maytag Corporation founder, rescued the brewery and with it the steam beer style. Anchor has since trademarked the term “Steam Beer” and all subsequent renditions of the style are now termed California common