In an otherwise fine Explainer column in Slate as to why American beer is generally on the weaker side alcohol-wise, Brian Palmer unloads a whopper:
Modern American beer enthusiasts tend to sneer at the two or three mass-produced beers that have dominated the industry for decades, but their success has little to do with corporate trickery, market manipulation, or the effects of Prohibition on smaller brewers. Nineteenth-century Midwestern lagers simply beat other styles of beer in the American market. Mass-marketed lagers were the first beers to truly catch on in the United States, and they have never relinquished that position. [emphasis mine]
The two or three mass-produced beers (presumably Palmer means those of Anheuser-Busch, Miller and Coors) have, in fact, manipulated the market time and again since the Second World War. Nothing illegal about it, of course, but they routinely gobbled regional competitors (often continuing the brands without necessarily touting the new ownership); choked distribution networks (most notably in the 1990s, when Anheuser-Busch launched its 100 percent share of mind campaign to push distributors to drop craft brands); brought the hammer down through media buys and spin (beer folk still remember the Oct. 13, 1996 Dateline segment wherein all of craft beer was called into question by mega-NBC advertiser Anheuser-Busch); and launched so-called phantom crafts (Blue Moon, Plank Road, etc.) to corner the fastest-growing segment in American beer.
As for the effects of Prohibition on smaller brewers, think of it this way: There were thousands of American breweries, big and small, before 1920. After Repeal in 1933, the landscape, as Palmer notes, came to be dominated by the those two or three mass-produced beers; and the number of American breweries only climbed into the thousands (as in plural, not just more than 1,000) in the last couple of years.