During the 19th century, lager was a popular American beer. By definition, the drink required cold fermentation, but in rugged Northern California where miners were thirsty for brew, refrigeration (and therefore cold fermentation) was a rare luxury.
So innovative brewers struck a compromise. They used a lager yeast, but fermented their beverages at higher temperatures usually reserved for ales. The result was a malty beer, with an aggressive hop bitterness and generous carbonation. They called it a steam beer.
There are several theories as to where the name comes from, the favored version being that due to the high carbonation, the bar keep had to tap it and let off some “steam” before dispensing it.
It was generally considered a blue-collar beer until Anchor Brewing Company refined the drink and trademarked the name in 1981. They claim the term “steam” referred to the steam that emanated from the roof of their brewery in San Francisco. Though the brewery’s history has been a rocky one, complete with earthquakes and prohibition, they have been brewing steam beer since 1896.