In early colonial times, letter writers sent their correspondence to friends, merchants, and Native Americans via foot or horseback. Most of this correspondence, however, was between the colonists and family members back home in England. In 1633, the first official notice of postal service in the colonies appeared. At the heart of the “mailing industry” is the U.S. Postal Service, which has been active for over two centuries. An explosion of mail in the late nineteenth and early twentieth century drove post offices and large-volume mailers to work together to handle mail more efficiently.