Coors - established in 1873
Budweiser - established in 1876
Although as already mentioned neither of those is the same now as it was then, although Coors probably says Old West more than Budweiser. If you can find it in your area I like the beers from the Breckenridge Brewery here in Denver. They make three beers that are actually aged in barrels but I suspect that those are only available in the Colorado area.