| Official Name: | Pompeys Pillar, Montana |
| Settlement Type: | Census Designated Place |
| Pushpin Map: | Montana#USA |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Montana |
| Subdivision Type2: | County |
| Subdivision Name2: | Yellowstone |
| Unit Pref: | Imperial |
| Area Footnotes: | [1] |
| Area Total Km2: | 0.51 |
| Area Land Km2: | 0.51 |
| Area Water Km2: | 0.00 |
| Area Total Sq Mi: | 0.20 |
| Area Land Sq Mi: | 0.20 |
| Area Water Sq Mi: | 0.00 |
| Population As Of: | 2020 |
| Population Total: | 51 |
| Population Density Km2: | 100.91 |
| Population Density Sq Mi: | 261.54 |
| Timezone: | Mountain (MST) |
| Utc Offset: | -7 |
| Timezone Dst: | MDT |
| Utc Offset Dst: | -6 |
| Elevation Ft: | 2894 |
| Coordinates: | 45.9906°N -107.9503°W |
| Postal Code Type: | ZIP code |
| Postal Code: | 59064 |
| Area Code: | 406 |
| Blank Name: | GNIS feature ID |
| Blank Info: | 2804324 |
Pompeys Pillar is a Census Designated Place in Yellowstone County, Montana, United States and has a postal ZIP code (59064).
The town of Pompeys Pillar was founded in 1907 and was named after and situated less than a mile east of Pompeys Pillar National Monument, a 150 ft. tall sedimentary rock formation best known for William Clark's inscription of his name and the date July 25, 1806 on its surface. The site also has significant evidence of human activity spanning an estimated 11,000 years.
The town of Pompeys Pillar was first planned out as a railroad station within the Huntley Project, an irrigation project managed by the United States Bureau of Reclamation.
A Catholic church and a Union Congregational church once existed in Pompeys Pillar. The Northern Pacific Railroad connected the town to Billings, about 29 miles southwest. A post office currently operates in the community.
Pompeys Pillar National Monument was created in 2001 and placed under the jurisdiction of the Bureau of Land Management. In 2006 a new visitor's center and museum complex opened, coinciding with the bicentennial of the Lewis and Clark Expedition. The site also has a small gift shop and other amenities.[2]
The school district is Huntley Project K-12 Schools, a K-12 unified school district.[3]