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Steam beer is a highly effervescent beer made by brewing lager yeasts at warm fermentation temperatures. It has two distinct but related meanings:
- Historic steam beer produced in California from the mid-19th century to the mid-20th century;
- Modern California common beer, a competition category name for the beer family which includes Anchor Steam beer.
Historic steam beer, associated with San Francisco and the U.S. West Coast, was brewed with lager yeast without the use of refrigeration. It was an improvised process, originating out of necessity, perhaps as early as the Gold Rush, at least 1860 in Nevada. It was considered a cheap and low-quality beer[improper synthesis?], as shown by references to it in literature of the 1890s and 1900s.
Modern steam beer, also known as California common beer, was originated by Anchor Brewing Company, which trademarked the name Anchor Steam Beer in 1981. Although the modern company has corporate continuity with a small brewery which was still making traditional steam beer in the 1950s, Anchor Steam beer is a craft-brewed lager. The company does not claim any close similarity between its present day product and turn-of-the-20th-century steam beer.
Explanations of the word "steam" are all speculative. The carbon dioxide pressure produced by the process was very high, and one possibility is that it was necessary to let off "steam" before attempting to dispense the beer. According to Anchor Brewing, the name "steam" came from the fact that the brewery had no way to effectively chill the boiling wort using traditional means. So they pumped the hot wort up to large, shallow, open-top bins on the roof of the brewery so that it would be rapidly chilled by the cool air blowing in off the Pacific Ocean. Thus while brewing, the brewery had a distinct cloud of steam around the roof let off by the wort as it cooled, hence the name. It is also possible that the name derives from "Dampfbier" (literally "steam beer"), a traditional German beer that was also fermented at unusually high temperatures and that may have been known to 19th-century American brewers, many of whom were of German descent.
Brewing process 
In 19th-century California, not only ice, but even sources of naturally cold water, were probably unavailable to brewers. California brewers were forced to use lager yeast at higher ale temperatures.
Final flavors of beer are influenced by the strain of yeast and the fermentation temperature. Lager yeast is best used at temperatures from 58 to 48 °F (14 to 9 °C). Classic lagering of beers takes place over a period of time from weeks to many months at a temperature of 37 °F (3 °C). Lager yeasts are bottom fermenting, which is to say that after fermentation they settle on the bottom of the fermenter.
Ale yeast is best used at temperatures from 55 to 75 °F (13 to 24 °C). Fermentation by ale yeasts produces a beer that has a distinctive ale flavor. Ale yeasts are top-fermenting, that is they settle out on top of the wort after fermenting (fermentation itself takes place in a suspension). Steam Beer uses bottom fermenting lager yeasts at ale temperatures, which results in a very distinctive flavor profile that includes both ale and lager characteristics.
While steam beer is considered a specialty microbrew style of beer today, it was originally a cheap beer made for blue collar workers. Wahl and Heinus's American Handy Book of Brewing and Malting (1902) describes California Steam Beer as “a very clear, refreshing drink, much consumed by the laboring classes.” And while Anchor Steam is an all-barley malt beer, additives were often used in the early days. According to the book, "Malt alone, malt and grits, or raw cereals of any kind, and sugars, especially glucose, employed in the kettle to the extent of 331⁄3 percent... Roasted malt or sugar coloring is used to give the favorite amber color of Munich beer."
In literature 
- The first day I worked in the bowling alley, the barkeeper, according to custom, called us boys up to have a drink after we had been setting up pins for several hours. The others asked for beer. I said I'd take ginger ale. The boys snickered, and I noticed the barkeeper favoured me with a strange, searching scrutiny. Nevertheless, he opened a bottle of ginger ale. Afterward, back in the alleys, in the pauses between games, the boys enlightened me. I had offended the barkeeper. A bottle of ginger ale cost the saloon ever so much more than a glass of steam beer; and it was up to me, if I wanted to hold my job, to drink beer.
As a budding writer, "a wild band of young revolutionists invited me as the guest of honour to a beer bust" and was challenged to a drinking contest.
- I'd show them, the young rascals.... These unlicked cubs who thought they could out-drink me! Faugh! It was steam beer. I had learned more expensive brews. Not for years had I drunk steam beer...
- It was Sunday, and, according to his custom on that day, McTeague took his dinner at two in the afternoon at the car conductors' coffee-joint on Polk Street. He had a thick gray soup; heavy, underdone meat, very hot, on a cold plate; two kinds of vegetables; and a sort of suet pudding, full of strong butter and sugar. On his way back to his office, one block above, he stopped at Joe Frenna's saloon and bought a pitcher of steam beer. It was his habit to leave the pitcher there on his way to dinner.... By and by, gorged with steam beer, and overcome by the heat of the room, the cheap tobacco, and the effects of his heavy meal, he dropped off to sleep.
When he marries, his wife convinces him to adopt more refined habits:
- She broke him of the habit of eating with his knife, she caused him to substitute bottled beer in the place of steam beer, and she induced him to take off his hat to Miss Baker, to Heise's wife, and to the other women of his acquaintance.
California common beer 
According to the Beer Judge Certification Program, the term California common beer, designated style 7B, is "narrowly defined around the prototypical Anchor Steam example", and other commercial examples include Skyscraper Brewing Company Lug Nut Lager, Southampton West Coast Steam Beer, Old Dominion Victory Amber, Flying Dog Old Scratch Amber Lager, Schlafly's Pi Common, Linden Street Common Lager and Eagle Steam Beer. The style "showcases the signature Northern Brewer hops (with woody, rustic or minty qualities) in moderate to high strength", is fermented with "a lager yeast, but one that was selected to thrive at the cool end of normal ale fermentation temperatures", and was traditionally fermented in open fermenters.
Other kinds of "steam beer" 
Adam Wood Steam Brewery is listed as having been sold in 1859.
A British brewery, the Lincolnshire Steam Beer Co., derives its name from the steam-powered brewing machinery.
When Canadian brewer Sleeman introduced a product called Steam Beer in Canada in 1999, Anchor sued for trademark infringement, since it had trademarked the term "steam beer" in Canada ten years earlier. Canadian courts dismissed the suit and subsequent appeals, ruling that Anchor's Canadian trademark was invalid, since the beer had not been marketed in Canada up to that time. After Sapporo bought Sleeman in a $400-million takeover in 2006, Sleeman's production of Steam Beer was discontinued.
In Richmond, Virginia the remains of a former Yuengling brewery along the James River were once called David Yuengling Jr.'s James River Steam Brewery and are located at (or near) 912 East Main St.
St. Louis guide for citizens and strangers shows advertising copy for J.F. Boyd & Co. St. Louis Ale, Porter and Lager Beer Steam Brewery.
Derecho Common was issued by the Port City Brewing Company of Alexandria, VA after the power outages related to the June 2012 North American derecho resulted in a tank of Port City's beer fermenting as a steam beer due to loss of refrigeration. 
- "Carson Brewing Company". United States National Park Service. Retrieved 9 May 2013.
- Papazian, Charlie (2003). The Complete Joy of Home Brewing: 3rd Edition.
- "Citation: Anchor Brewing Co. v. Sleeman Brewing & Malting Co. Ltd., 2001 FCT 1066, (2001), 1 F.C. D-15, Docket: T-1158-99". Office of the Commissioner for Federal Judicial Affairs Canada. 2001-09-28. Retrieved 2010-01-20.
- "Sapporo acquisition of Sleeman on tap". CBC News. 2006-08-11. Retrieved 2010-01-20.
- Foyston, John. "Widmer releases O'Ryely IPA, Columbia Common Spring Ale and three KGBs". Oregon Live, LLC. Retrieved 3 May 2013.
-  - Detailed historical article by Martin Lodahl from Brew Your Own magazine
- California Steaming - Article about the beer style in Brewing Techniques magazine
- Anchor Brewing Co. Official web site of the Anchor Steam Beer brewer