150 years ago the matching pants and coats of the cut we know today were actually considered casual. In the early 1800s, men wore fitted short coats with tails. In the mid-1800s, men started wearing long frock coats with a cinched-in waist. The tailcoats were relegated to formal evening wear. In the late 1800s, the more casual "sack suits" (as they were called) began replacing frock coats. Today, suits have been replaced in most business environments by business casual shirtsleeves and golf shirts. The history of men's fashion is one of an ever-increasing tendency toward clothing that is more casual.