| Official Name: | St. Xavier, Montana |
| Settlement Type: | Unincorporated community and census-designated place |
| Mapsize: | 250px |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Montana |
| Subdivision Type2: | County |
| Subdivision Name2: | Big Horn |
| Unit Pref: | Imperial |
| Area Footnotes: | [1] |
| Area Total Km2: | 14.49 |
| Area Land Km2: | 14.49 |
| Area Water Km2: | 0.00 |
| Area Total Sq Mi: | 5.60 |
| Area Land Sq Mi: | 5.60 |
| Area Water Sq Mi: | 0.00 |
| Population As Of: | 2020 |
| Population Total: | 78 |
| Population Density Km2: | 5.38 |
| Population Density Sq Mi: | 13.94 |
| Timezone: | Mountain (MST) |
| Utc Offset: | -7 |
| Timezone Dst: | MDT |
| Utc Offset Dst: | -6 |
| Elevation Ft: | 3074 |
| Coordinates: | 45.4611°N -107.7217°W |
| Postal Code Type: | ZIP code |
| Postal Code: | 59075[2] |
| Area Code: | 406 |
| Blank Name: | FIPS code |
| Blank Info: | 30-65650 |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 776137 2409234 |
St. Xavier is an unincorporated community and census-designated place (CDP) in Big Horn County, Montana, United States. The CDP population was 83 at the 2010 census.[3]
According to the United States Census Bureau, the CDP has a total area of 14.6km2, of which 14.4km2 is land and 0.2km2, or 1.12%, is water.[3] It is located on the Crow Indian Reservation[4] along the Bighorn River.
As of the census[5] of 2000, there were 67 people, 20 households, and 18 families residing in the CDP. The population density was 12.0 people per square mile (4.6/km). There were 36 housing units at an average density of 6.5 per square mile (2.5/km). The racial makeup of the CDP was 38.81% White, 52.24% Native American, 7.46% from other races, and 1.49% from two or more races. Hispanic or Latino of any race were 22.39% of the population.
There were 20 households, out of which 55.0% had children under the age of 18 living with them, 70.0% were married couples living together, 15.0% had a female householder with no husband present, and 10.0% were non-families. 10.0% of all households were made up of individuals, and none had someone living alone who was 65 years of age or older. The average household size was 3.15 and the average family size was 3.33.
In the CDP, the population was spread out, with 32.8% under the age of 18, 13.4% from 18 to 24, 31.3% from 25 to 44, 16.4% from 45 to 64, and 6.0% who were 65 years of age or older. The median age was 28 years. For every 100 females, there were 67.5 males. For every 100 females age 18 and over, there were 95.7 males.
The median income for a household in the CDP was $19,722, and the median income for a family was $19,722. Males had a median income of $11,250 versus $15,500 for females. The per capita income for the CDP was $11,578. There were 25.0% of families and 40.7% of the population living below the poverty line, including 70.4% of under eighteens and none of those over 64.