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Welcome to Keystone ...

The town of Keystone is located in Pennington County<1>.

Keystone was established in 1883.

From the  Census Estimates for 2019, Keystone has a population of 345 people<2> (see below for details).

The community of Keystone is 4,360 feet [1,329 m] above sea level.<3> In other words, the altitude of Keystone is about ¾ mile [or ~1¼ km] above sea level.

Time Zone: Keystone lies in the Mountain Time Zone (MST/MDT) and observes daylight saving time

Area Code for Keystone: 605

The ZIP code for Keystone: 57751<4>

Population Details ...

Taken from the 2019 Census Estimates, Keystone had an population of 345 people. This is an increase of 2.37% since the 2010 Census (or an increase of 10.93% since the 2000 Census).

At the time of the 2010 Census, Keystone had a population of 337 people. This makes Keystone the county's 11th most populous community.

The population of Keystone represents 0.04% of the total population of South Dakota (which has 814,180 people), making it the state's 197th most populous community.

With a 2010 count of 337 people, the population of Keystone increased 8.36% from the 2000 Census (with a count of 311 people).

More information can be found on the Census Page for Keystone.

Communities Also Named Keystone ...

Using our Gazetteer, we found that there are 44 communities that are also named Keystone - they are located in Alabama, Arkansas, California (2), Colorado (3), Delaware, Florida, Indiana (2), Iowa, Louisiana (2), Michigan, Minnesota (2), Missouri (2), Montana, Nebraska (2), Nevada (4), North Dakota (2), Ohio (2), Oklahoma, Pennsylvania (5), Tennessee, Washington (3), West Virginia (2), Wisconsin and Wyoming.

For more information, see our Tidbits & Trivia Page for Keystone.

Communities near Keystone ...

We have created a list of 10 communities that are near Keystone.

  • Rapid City
    (16 miles [25.7 km] to the northeast)
  • Rapid Valley
    (18 miles [29 km] to the northeast)
  • Spokane ‑ Historic
    (4 miles [6.4 km] to the southeast)
  • Custer
    (12 miles [19.3 km] to the southwest)
  • Sanator
    (16 miles [25.7 km] to the southwest)
    • Sanator is located in Custer County
    • Jump to our Gazetteer entry for Sanator
    • Estimated population in 2014: 1,350 people
  • Hill City
    (8 miles [12.9 km] to the west)
  • Johnson Siding
    (13 miles [20.9 km] to the north)
  • Murphy
    (17 miles [27.4 km] to the northeast)
    • Murphy is located in Pennington County
    • Jump to our Gazetteer entry for Murphy
    • Estimated population in 2014: 482 people
  • Sheridan ‑ Historic
    (6 miles [9.7 km] to the northwest)
    • Sheridan is located in Pennington County
    • Jump to our Gazetteer entry for Sheridan
    • Estimated population in 2014: 447 people
  • Hermosa
    (11 miles [17.7 km] to the east)

To Help With Your Genealogy Research ...

We have a couple of sections for those tracing their genealogy.

We created a list of cemeteries that are in the area around Keystone. Our list includes the location of those cemeteries and we provide an overhead view. See our Cemetery List for Keystone.

Using the information from an 1895 Atlas, we've created a list of communities that were in the area of Keystone. Our list includes information such as whether the 1895 community had a post office or railroad service. See our List of 1890's Communities around Keystone.

We also have a detailed list of newspapers that have been published in the area around Keystone. See our Newspapers Page for Keystone.

TripAdvisor Tourism Pages for Keystone ...

Looking for more information about Keystone? A wonderful source is the TripAdvisor website. We always start with the TripAdvisor Tourism page, where you can read an overview with links that will help you find lodging, restaurants and attractions.

In addition to the Tourism page for Keystone, there are neighboring communities that also have Tourism pages. More information about those communities can be found on our TripAdvisor Page for Keystone.

Adding Keystone to Our Gazetteer ...

We originally found mention of Keystone in both the FIPS-55 and the GNIS. For more information, see the FIPS and GNIS Codes sections on our Miscellaneous Page.

From our notes, the earliest published mention we've found (so far) for Keystone was in the document titled List of Post Offices from Cameron Blevins and Richard Helbock.<6>

From that list, the Keystone post office opened in 1892.

For more details, see References and Mentions for Keystone.

Footnotes ...

<1>If you're interested in how the shape of South Dakota's counties, including Pennington, have changed over time, we recommend the Atlas of Historical County Boundaries.
<2>Population counts have been provided by the U.S. Census Bureau. For more detail, please visit our Census Page for Keystone.
<3>The elevation is an estimate for the area around Keystone - it will be higher in some places and lower in others.
<4>ZIP Codes have been created by the United States Postal Service (USPS) as a way of grouping addresses to make delivery more efficient. The boundaries of the ZIP Code can be changed, re-assigned, eliminated or overlapped with other ZIP Codes. So keep in mind that any given ZIP Code is only 'loosely' associated with a town (such as Keystone). When looking for a ZIP Code, whether Keystone or elsewhere, it's always best to check the website of the United States Postal Service (USPS).
<5>While we're fans and frequent users of TripAdvisor, you should know that we're also members of the TripAdvisor affiliate program.
<6>A copy of the Blevins & Helbock Post Office list with background information can be found at:

      https://cblevins.github.io/us-post-offices/data-biography/