USPS processing equipment u201creadsu201d mail from the bottom up. Contrary to a lot of these answers, the proper addressing format is:Line 1: Suite or Apartment number if applicableLine 2: Street addressLine 3: City/State/ZIPSuch as:NameApt 123456 Main Street SEAnytown USA 12345Alternatively, the suite or apartment number can immediately follow the street address on the same line. It should NOT be placed on Line 2.If you are mailing to a different country, the country name should be the very bottom line.One of my positions while at USPS included assisting commercial customers design envelopes, including proper addressing formats and computer markings (FIMs and barcodes).