Covers—typically envelopes with postage—tell the philatelic history of communication and structured systems of mail delivery within and among countries. When a patron deposits a piece of mail into a drop box, the creation of a ‘cover’ begins. The term ‘cover’ generally refers to any item that has passed through a mail system and so is ‘postally used’.
When speaking of covers and U.S. philately, one must remember that the land comprising the contiguous forty-eight states was not under unified control until 1854—i.e., following the Gadsden Purchase. The preceding eighty years had seen England with controlling interests on the east coast from Georgia and Mississippi and north to the Canadian border. France had controlled the interior from Louisiana to Canada. Spain had controlled Florida, and Mexico had held a vast territory that included almost everything west of Louisiana to the coast and north to the Oregon-Washington territory. After the Revolution, a new American system with roots in the British colonial post gradually replaced the existing systems of communication used by these countries and their colonial holdings. The new system generated covers which document the ways in which the new system responded to westward expansion, to national disunity and international wars, to the evolution of the transportation industry, to burgeoning business, and to America’s own empire building.