In an attempt to cut $2 billion from its budget, the United States Postal Service will end Saturday delivery on Aug. 1. That means, for the first time ever, Americans will receive mail only five days a week (packages, however, are exempt from the change).

That's the bad news. But there's still some good news here: The USPS, by one metric, is still the very best internationally at its most crucial task: Delivering mail.

Researchers Alberto Chong, Rafael La Porta, Florencio Lopez-de-Silanes, and Andrei Shleifer sent letters to 10 fake addresses in 159 countries. The whole idea was to test government efficiency, by seeing how long it took to return the letters to the senders.

All these countries, the researchers note, subscribe to an international postal convention (the Universal Postal Union, coordinated by the United Nations), which requires them to return letters they cannot deliver.

Not all are that great at it: Only 60 percent of the letters actually came back to the researchers.

Among the countries that returned all 10 letters, the USPS was far and away the fastest to do so.

How did the USPS do so well? The researchers chalk it up to two main factors: Management and technology. Mail services with more robust databases have an easier task in returning mis-addressed labels. "If postcode database includes street names, in which case the non-existence of the street name, and therefore the incorrectness of the address, would pop out immediately as soon as the envelope is machine read," they note.

The native language of the country matters too. Countries that use the Latin alphabet returned 12 percent more letters than those that used other alphabets. Probably not enough to encourage countries to choose a new native language, but one factor that does help a letter get where it’s going a bit faster.