A person of good character, age 18 or older, who is a citizen of United States, and is lineally descended from an ancestor who served in any capacity to aid in the development and execution of the American postal system during the period 1607 to 1900, is eligible for membership. Services include: Postmaster General, Postmaster, postal official, postal surveyor, postal inspector of township or county, tavern keeper, inn keeper, book seller, printer, Pony Express rider, stagecoach operator, ferrymen, ship captain, steamboat captain, freight office official, railroad mail service superintendent or clerk, and surveyor or builder of roads and bridges.