With the introduction of more affordable postal rates about 1845, the establishment of postal routes in 1851, and free city mail delivery in 1863, manufactured envelopes to enclose correspondence became commonplace. Previously letters were folded to create their own enclosure. For businesses, envelopes (and the complementary letterhead and billhead) provided yet another means to visually mass market their product or service. Designs depicted exteriors of factories and storefronts, the products for sale, and on occasion rare commercial interiors. The illustrations can often show some of the few known depictions of the commercial enterprises they represent, while the addresses, postmarks, and stamps provide information about the daily lives of the business’s patrons.