A first-class letter mailed from Salem, Va., to Lenexa, Kan., takes an average of three days, according to the map server from the U.S. Postal Service (USPS). Mail is not guaranteed to arrive at its destination in that time frame. Faster delivery by Priority Mail is available for higher fees.
Priority Mail Express is the fastest delivery method for the Postal Service. Express service is overnight to most locations in the United States with a money-back guarantee from the USPS. As of July 2014, a first-class letter costs 49 cents to send anywhere in the United States. First-class mail is for packages up to 13 ounces.