In what year did they first put commercial beer in cans?

The first commercial beer available in cans began in 1935 in Richmond, Virginia. Not long after that, sodas, with their higher acidity and somewhat higher pressures, were available in cans. The key development for storing beverages in cans was the interior liner, typically plastic or sometimes a waxy substance, that helped to keep the product's flavor from being ruined by a chemical reaction with the metal. Another major factor for the timing was the repeal of Prohibition in the United States at the end of 1933.

In 1935, the small brewery at Felinfoel was the first brewery outside the USA to commercially can beer. Prior to this time, beer was only available in barrels or in glass bottles. From this time, lightweight tin cans could be used. Felinfoel Brewery was a major supplier to British armed forces abroad in the Second World War - cans saved a great deal of space and weight for wartime exports compared to glass bottles, and did not have to be returned for refilling. These early cans did not have a 'pull tab', instead they had a 'crown cork' (beer bottle top). All modern UK canned beer is descended from these small, early cans which helped change the drinking and beer-buying habits of the British public.