Once again many thanks to Cernjul Viviana for this wonderful cover posted from Argentina!
The stamps belong to the "UPAEP America, Old Mail Boxes" series, issued in 2011.
The second cover was posted from the USPS United States Post Office Midlakes Station in Bellevue, Washington on 21 Nov 2011. Many thanks to Bryon Peterson!
The beautiful stamps on this cover are from a sheet of 12 stamps, entitled "Pioneers of American Industrial Design", issued on 29 Jun 2011. Honoring 12 of the nation's most important and influential industrial designers, the stamps depict everything from furniture and electric kitchen appliances to corporate office buildings and passengers trains, the work of these designers defined the look of modern America, and in doing, revolutionized the way Americans live and work.