1859, slang shortening of public house (see public (adj.)), which originally meant "any building open to the public" (1570s), then "inn that provides food and is licensed to sell ale, wine, and spirits" (1660s), and finally "tavern" (1768). Simple public (n.) as short for public house is attested from 1709 and might have been the intermediate form. Pub crawl is attested by 1910 in British slang. Pub rock is from 1973 in England; popular in U.S. from 1976.
When, in the late '60s, rock 'n' roll suddenly became rock, there sprang up a network of bands that sought to preserve the old styles, that resisted the trend toward larger and larger concert halls. Because these groups preferred to play one-nighters on Britain's club circuit, their music came to be known as "pub rock." ["U.S. gets 'pub rock,'" Washington Post article in Newark (Ohio) Advocate, April 1, 1976]