1868:
population of U.S: 36.5 million
per capita consumption: 4.8 gallons

1878:
47.8 million
6.1 gallons

1888:
60.3 million
11.7 gallons

1898:
73.3 million
15.5 gallons

1908:
88.7 million
15.5 gallons
Note: nearly 50% of Americans lived under some form of local/state prohibition. Pre-prohibition per capita consumption peaked in 1911 with 21 gallons, a level also reached in 1913 and 1914

1918:
102.9 million
15.1 gallons
number of breweries: 1,092 (fiscal year)
Note: On December 1, 1918, the nation's breweries halted operations, thanks to a presidential order aimed at rationing the nation's supplies of grain and fuel.

1938:
129.7 million
12.9 gallons
696 breweries

1948:
146 million
18.5 gallons

1958:
173.4 million
15 gallons
252 breweries

1968:
199.3 million
16.7 gallons
163 breweries

1978:
222 million
22 gallons
89 breweries

1988:
244.4 million
22.6 gallons
245 breweries

1997:
267.6 million
20.6 gallons
1,698 breweries (estimated)

2006:
299.3 million (estimated)
21.6 gallons
1,905 breweries

Sources:
United States Brewers' Association Almanac, 1940
Beer Institute, including the 1999 Brewers' Almanac