Park Counties in Montana and Wyoming are among the very few pairs of counties in the United States with the same name to border each other across state lines.

• Custer National Forest
  Custer National Forest
  Custer National Forest is located primarily in the southern part of the U.S. state of Montana but also has separate sections in northwestern South Dakota. With a total area of 1,278,279 acres , the forest comprises over 10 separate sections...
  
   (part)
• Gallatin National Forest
  Gallatin National Forest
  Founded in 1899, Gallatin National Forest is located in south central Montana, United States. The forest comprises 2.1 million acres and has portions of both the Absaroka-Beartooth and Lee Metcalf Wilderness areas within its boundaries...
  
   (part)
• Lewis and Clark National Forest
  Lewis and Clark National Forest
  Lewis and Clark National Forest is located in west central Montana, United States. Spanning , the forest is managed as two separate zones. The eastern sections, under the Jefferson Division, is a mixture of grass and shrublands dotted with "island" pockets of forested areas. Here, cattle leases to...
  
   (part)
• Yellowstone National Park
  Yellowstone National Park
  Yellowstone National Park, established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872, is a national park located primarily in the U.S. state of Wyoming, although it also extends into Montana and Idaho...
  
   (part)

As of the census

Census

A census is the procedure of systematically acquiring and recording information about the members of a given population. It is a regularly occurring and official count of a particular population. The term is used mostly in connection with national population and housing censuses; other common...

of 2000, there were 15,694 people, 6,828 households, and 4,219 families residing in the county. The population density

Population density

Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans...

 was 6 people per square mile (2/km²).