Keystone SD ZIP Code
Keystone city is located in South Dakota State, Pennington County and has a unique zip code assigned by the US Postal Service Office.
You can search for the Keystone SD zip code by its streets and block numbers if we have some of the Keystone streets loaded in our website
Keystone Area Code is 605 and Time Zone is Mountain (GMT -07:00).
Keystone Zip Code - South Dakota
The US ZIP Code basic format consists of five decimal numerical digits assigned to the Keystone City. An extended ZIP+4 code, introduced in the 1980s, includes the five digits of the Keystone ZIP code, a hyphen, and four more digits that determine a more specific location within a given ZIP code in Keystone, South Dakota.
The Keystone Zip Code is 57751.
If you want to send a mail to Keystone City, you should use the 57751 Zip Code.
In 1983, the U.S. Postal Service introduced an expanded Keystone ZIP code system that it called ZIP+4, often called "plus-four codes", "add-on codes", or "add ons". A ZIP+4 code uses the basic 57751 Zip code plus four additional digits to identify a geographic segment within the five-digit delivery area, such as a Keystone city block, a group of apartments, an individual high-volume receiver of mail or any other unit that could use an extra identifier to aid in efficient mail sorting and delivery in South Dakota.