Before AC, Americans mostly lived in cold parts of the country, and heated to get to a comfortable temperature. AC allowed comfortable temperatures in warmer a

Before AC, Americans mostly lived in cold parts of the country, and heated to get to a comfortable temperature. AC allowed comfortable temperatures in warmer areas, and there's been a huge migration to the sun belt. This process has decreased our energy needs, because the average American now lives in a place where the climate is, on average, closer to a comfortable living temperature than they did a century ago.