Petroleum County Demographics
A map of Petroleum County's Population by Race
Petroleum County, Montana has an estimated population of 447, a decrease from the 496 recorded in the 2020 Census. The population is 98.9% White, 0.7% Asian, 0.4% Native American/Other, 0.0% Black, 0.0% Hispanic, and 0.0% Multiracial. This demographic dot map shows the population of Petroleum County, with one dot drawn for each person counted by the Census, color-coded by race.
Petroleum has become considerably less racially diverse since the 2020 Census. It is considerably less diverse than Montana overall. Demographers use a diversity index to measure the probability that two randomly selected individuals belong to different racial or ethnic groups. In Petroleum County, that probability was 11.5% in 2020 and 2.2% in the most recent ACS estimates.
Petroleum County is ranked the 56th most populous county in Montana, out of 56 counties. Petroleum County was ranked the 56th most populous county in the 2020 Census.
Petroleum County's White Population
442 residents of Petroleum County, or 98.9% of the population, identify as White. The share of White residents in Petroleum County is significantly higher than in Montana overall, where 83.6% of the population is White. Petroleum County ranks 4th statewide in terms of White residents as a share of the population, out of 56 counties.
Since the 2020 Census, Petroleum County's White population has declined by an estimated 5.2%. White residents' share of Petroleum County's population has increased from 94.0% to 98.9%.
Petroleum County is more White than neighboring Musselshell County (86.6% White), Fergus County (92.4% White), Yellowstone County (83.4% White), Golden Valley County (90.3% White), and Phillips County (81% White).
Petroleum County's Black Population
0 residents of Petroleum County, or 0.0% of the population, identify as Black. The share of Black residents in Petroleum County is comparable to the share in Montana overall, where 0.4% of the population is Black. Petroleum County ranks 52nd statewide in terms of Black residents as a share of the population, out of 56 counties.
Since the 2020 Census, Petroleum County's Black population has grown from 0 to an estimated 0. Black residents' share of Petroleum County's population has remained roughly unchanged at 0.0%.
Petroleum County is less Black than neighboring Fergus County (0.6% Black), Yellowstone County (0.4% Black), Golden Valley County (0.8% Black), and Phillips County (0.2% Black).
Petroleum County's Asian Population
3 residents of Petroleum County, or 0.7% of the population, identify as Asian. The share of Asian residents in Petroleum County is comparable to the share in Montana overall, where 0.8% of the population is Asian. Petroleum County ranks 54th statewide in terms of Asian residents as a share of the population, out of 56 counties.
Since the 2020 Census, Petroleum County's Asian population has grown from 0 to an estimated 3. Asian residents' share of Petroleum County's population has increased from 0.0% to 0.7%.
Petroleum County is more Asian than neighboring Musselshell County (0% Asian), and Golden Valley County (0% Asian). Petroleum County is less Asian than neighboring Phillips County (0.8% Asian).
Petroleum County's Hispanic Population
0 residents of Petroleum County, or 0.0% of the population, identify as Hispanic. The share of Hispanic residents in Petroleum County is slightly lower than in Montana overall, where 4.6% of the population is Hispanic. Petroleum County ranks 54th statewide in terms of Hispanic residents as a share of the population, out of 56 counties.
Since the 2020 Census, Petroleum County's Hispanic population has declined by an estimated 100.0%. Hispanic residents' share of Petroleum County's population has decreased from 1.0% to 0.0%.
Petroleum County is less Hispanic than neighboring Musselshell County (4.3% Hispanic), Fergus County (2.4% Hispanic), Yellowstone County (6.6% Hispanic), Golden Valley County (4.3% Hispanic), and Phillips County (1.1% Hispanic).
Petroleum County's Native American/Other Population
2 residents of Petroleum County, or 0.4% of the population, identify as American Indian/Alaska Native/Native Hawaiian/Pacific Islander/Other. The share of Native American/Other residents in Petroleum County is lower than in Montana overall, where 5.9% of the population is Native American/Other. Petroleum County ranks 56th statewide in terms of Native American/Other residents as a share of the population, out of 56 counties.
Since the 2020 Census, Petroleum County's Native American/Other population has grown from 0 to an estimated 2. Native American/Other residents' share of Petroleum County's population has remained roughly unchanged at 0.4%.
Petroleum County is less Native American/Other than neighboring Musselshell County (5.8% Native American/Other), Fergus County (2.1% Native American/Other), Yellowstone County (4.1% Native American/Other), Golden Valley County (0.8% Native American/Other), and Phillips County (8.1% Native American/Other).
Petroleum County's Multiracial Population
0 residents of Petroleum County, or 0.0% of the population, identify as Multiracial. The share of Multiracial residents in Petroleum County is slightly lower than in Montana overall, where 4.7% of the population is Multiracial. Petroleum County ranks 16th statewide in terms of Multiracial residents as a share of the population, out of 56 counties.
Since the 2020 Census, Petroleum County's Multiracial population has declined by an estimated 100.0%. Multiracial residents' share of Petroleum County's population has decreased from 5.0% to 0.0%.
Petroleum County is less Multiracial than neighboring Musselshell County (3.3% Multiracial), Fergus County (1.9% Multiracial), Yellowstone County (4.7% Multiracial), Golden Valley County (3.8% Multiracial), and Phillips County (8.7% Multiracial).
Sources: Most recent population estimates are from the 2020-2024 American Community Survey 5-Year Estimates. 2020 population counts and map data are from 2020 Census State Redistricting Data. Geographic data are from Census TIGER/Line Shapefiles.