A letter, parcel or package of nearly any size can be delivered as quickly as overnight between any two cities in the continental United States. However, when sent via First Class mail, the same item could take up to three days for delivery between Kansas City and Virginia.
Rates for mailing are higher when sending mail overnight than when sending it First Class. A letter sent with a two-day guarantee incurs a rate increase of a minimum of $5, according to the United States Postal Service. All post offices consider factors such as the size and shape of the parcel, the weight and characteristics of the contents, insurance requirements, fragility and other special handling requirements before committing to a guaranteed domestic delivery date between U.S. cities. For specific rates and special handling requirements, one may bring the package to a local post office or other pack-and-ship retailer.