So millineries thrived. Not only did a woman need a hat because of the “dress code” of the time, but she also wanted a hat that was unique; one that made her look her best and was unlike any other hat in town, or even the area. This emphasis on uniqueness was so important that lawsuits were brought, milliner against milliner, on accusations that one had stolen another designs and claimed them as their own. And many times, these women won!
Millinery was considered a respectable job for women in a time when a woman working outside of the home was not considered altogether socially acceptable. Milliners rank 7
in women’s employment in the U.S. Census for 1870; housekeepers, servants and factory work rank only slightly higher. Some millineries in larger cities did have association with “back room” activities – gambling parlors, opium dens, and prostitution – but the vast majority of millineries were run by upstanding married women, usually of the upper middle classes. 

See the full article from “Examiner.com”