The farmer’s barn had to be built wisely because invariably it housed his greatest assets. This agricultural building was more important than his own house. Without a way to protect farm animals or store crops, early settlers had few ways to survive.
Barns were about common sense and usefulness—and economics, not style.
Later farms came to specialize in certain crops, and barns became specialized as well (dairy, fruit, grains, tobacco, poultry, etc.). What we think of as a classic barn with the gambrel roof is a dairy barn, but there were smaller barnlike structures for different types of animals or different kinds of crops.