In the United States, the upcoming autumnal equinox is marked on most calendars as the "first day of autumn." Similarly the solstices are commonly called the "first day of summer" and "first day of winter." However in most other languages -- and even in older discussions in English -- the solstices have names like "Midsummer's Day" and "Midwinter's Day."
Is there some sound reason (e.g. typical temperatures, asymmetrical sunrise/sunset times, thermal inertia, etc.) to consider a solstice as the first day of a new season, rather than the middle?
Also (perhaps less on-topic) is there any record of when the change in nomenclature took place in the U.S.? Are there similar discrepancies in other English-speaking countries or in other cultures?