The speed of mail traveling between Guam and the states varies depending on size and time of year. Light, first-class items generally take less than a week to or from the mainland, but larger first-class or Priority items can take a week or two. Fourth-class mail, such as magazines, are transported by sea after reaching Hawaii. Most residents use post office boxes or private mail boxes, although residential delivery is becoming increasingly available. Incoming mail not from the Americas should be addressed to "Guam" instead of "USA" to avoid being routed the long way through the U.S. mainland and possibly charged a higher rate (especially from Asia).

What determines the speed in which mail reaches Guam from the United States?