Express mail in the United States
The United States Postal Service (USPS) provides Priority Mail Express for domestic U.S. delivery, and offers two international Express Mail services, although only one of them is part of the EMS standard. One is called Priority Mail Express International and the other service is called Global Express Guaranteed (GXG). The latter having no relation whatsoever to "EMS" International service as provided by the EMS Cooperative.
The USPS Global Express Guaranteed (GXG), by which USPS offices act as drop locations for international packages which are then handled by FedEx international delivery network.
In some countries, import rules for packages received by courier services have different tax brackets and duties than parcels received on the postal system, and thus  EMS service (Express Mail International) is preferred over FedEx's co-branded Global Express Guaranteed.
The term Priority Mail Express International is often confused with their domestic service called Priority Mail Express, which is a specific classification of mail for domestic accelerated postal delivery within the U.S.
In 2013, the USPS changed the name of the service from "Express Mail International" to "Priority Mail Express International". This may lead to confusion, as "Priority Mail" is still used, and the packaging is very similar.
Special Delivery, a domestic accelerated local delivery service, was introduced on 3 March 1885 initially with a fee of 10¢ paid by a Special Delivery stamp. It was transformed into Express Mail, introduced in 1977 after an experimental period that started in 1970, although Special Delivery was not terminated until June 8, 1997.
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Modern USPS Domestic Delivery Express Mail And International Express Mail Delivery
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Priority Mail Express is an accelerated domestic mail delivery service operated by the United States Postal Service. It is able to provide overnight delivery to most locations within the continental United States and guaranteed delivery within 2 days. Unlike most other USPS delivery options which provide only delivery confirmation, Express Mail provides accurate, up-to-date tracking information, and insurance up to $100.
Priority Mail Express delivers 365 days a year, including Saturdays, Sundays, and federal holidays. Sunday/Holiday delivery incurs a charge of $12.50 in addition to standard rate. Unlike Priority Mail and First Class Package Mail, USPS provides real-time tracking information online and by phone for Priority Mail Express shipments.
Global Express Guaranteed (GXG) service is an international expedited delivery service provided through an alliance with FedEx Corporation. It provides guaranteed, date–definite service from Post Office facilities in the United States to a large number of international destinations. (See Countries and Cities Served Section of Publication 141, Global Express Guaranteed Service Guide, for destination service commitments.) Global Express Guaranteed delivery service is guaranteed to meet the specified service standards or the postage paid may be refunded. For almost all network destinations, liability insurance is provided for lost or damaged shipments.
Other private express carriers guarantee overnight or 2-day delivery by as early as 8:30 or 10:30 AM. Priority Mail Express offers 10:30 AM delivery where available for a $5.00 surcharge. Priority Mail Express also conveys other benefits under specific circumstances: U.S. patent applications and related documents transmitted to the United States Patent and Trademark Office via USPS Priority Mail Express carry the postmark date as the date of patent priority, so long as each document is mailed along with a signed certificate of mailing bearing the Priority Mail Express tracking number of the mailing label.
- "USPS Priority Mail Express". Retrieved 12 July 2017.
- United States Postal Service (2017-01-22). "220 Priority Mail Express International". USPS Postal Explorer. Archived from the original on 2007-10-11. Retrieved 2017-03-03.
- USPS Global Express Guaranteed International Mail Manual – Issue 35 (retrieved April 10, 2008)
-  is a co-branded service, part of an agreement between the USPS and FedEx
- Why can't Amazon.com ship by USPS EMS?>
- "Significant Dates in Postal History". Postal History. USPS. Retrieved 2010-10-01.
- "U.S. Postal Service – Summary statistics – USA Census numbers". allcountries.org. Retrieved 2010-10-01.
- "EM Sunday Holiday Premium" (PDF). USPS. Retrieved 2012-03-23.
- "USPTO - 513 Deposit as Priority Mail Express® with U.S. Postal Service [R-07.2015]". Retrieved 12 July 2017.