Here in Missouri, (north west) I'd say the avg. was around 150 lbs. We commonly have deer taken each year in the 240 lb. range field dressed. My best friend shot a 160" class green scored 8 pointer just this past rifle season that went 241 lbs. on a certified scale. I would imagine that it all depends on the area you are asking about.
Agricultural(?) states like Kansas, Iowa, Missouri, Illinois, ect. tend to have bigger bodied deer than states like Texas and so on.