It’s the unstoppable American beer style: the India Pale Ale. And now both the Anchor Brewing Company, the nation’s oldest craft brewery by more than a decade, and the Boston Beer Company, the nation’s largest craft brewery by a mile, have their own iterations as of early 2014: Anchor IPA and Samuel Adams Rebel IPA. It’s a significant milestone in American beer for two reasons.

First, for the aforementioned respective age and size of the two breweries. For decades now, neither has apparently seen the need for an IPA in its line-up. Anchor’s iconic Anchor Steam has carried the brewery, along with a few other fantastic offerings, including the groundbreaking Anchor Porter, the first American-made porter in modern times, and Anchor Christmas Ale, the first seasonal (actually, it’s very easy to rattle off firsts when it comes to Anchor). Boston Beer has, of course, long hung its hat on Samuel Adams Boston Lager, introduced in the mid-1980s and easily the biggest-selling craft beer brand ever; there are myriad other Sam Adams, but Boston Lager remains the longest-running constant.

The reality that both breweries jumped into the IPA stream decades in, when they didn’t need to and when there are so many other options out there, shows the seemingly unassailable position the IPA enjoys atop the pantheon of American craft beer. It is, quite simply, the style American craft brewers are most known for the world over; the Brits may have invented it (or so the story goes), but the Americans ran away with it, developing nearly every conceivable iteration: double, triple, quadruple, Belgian, porter, amber, red, white, etc., ad infinitum.

Interestingly enough, it was Anchor that unwittingly kicked things off (I write “unwittingly” because the San Francisco-based brewery was the only craft brewery in the nation for so long that it had little idea its ground-breaking beers were just that: moves that would be emulated over and over). Anchor Liberty Ale, introduced in 1975 with a then-whopping bitterness of perhaps 40 IBUs, represented a palatal shift not only in American beer but, I would argue, in American drinking period. It was bitter in a time when most people, beer drinkers included, preferred sweet: colas, juices, more colas, Miller Lite. Bitter was out; sugar packets next to the automatic coffee machine were in. The only thing comparable in American beer might have been the IPA out of regional Ballantine.

Times change. Within a decade of Anchor Liberty, there was West Coast-style trendsetter Sierra Nevada Pale Ale, a beer that surely would have been introduced as Sierra Nevada India Pale Ale if the style term were much in use even in beer circles. (It wasn’t. The Great American Beer Festival, for one, didn’t add an India Pale Ale category until 1989, its third year of awarding medals by styleAnchor Liberty Ale took the silver thenand it was not until the early 1990s that a new brewery, Lagunitas Brewing Company out of the San Francisco area, led its lineup with an IPA.) Within a quarter-century, there were all the iterations, too numerous to name, really, that continue to reverberate. And that now include ones from the oldest and the biggest.