St. Martin County Demographics

A map of St. Martin County's Population by Race

Race	2024 Pop	2020 Pop	2024 %	2020 %
White	32,398	32,919	63.1%	63.6%
Black	14,690	15,050	28.6%	29.1%
Hispanic	1,873	1,679	3.6%	3.2%
Multiracial	1,700	1,329	3.3%	2.6%
Asian	390	440	0.8%	0.8%
Native American/Other	302	350	0.6%	0.7%

St. Martin County, Louisiana has an estimated population of 51,353, a less than 1% change from the 51,767 recorded in the 2020 Census. The population is 63.1% White, 28.6% Black, 3.6% Hispanic, 3.3% Multiracial, 0.8% Asian, and 0.6% Native American/Other. This demographic dot map shows the population of St. Martin County, with one dot drawn for each person counted by the Census, color-coded by race.

St. Martin has become slightly more racially diverse since the 2020 Census. It is considerably less diverse than Louisiana overall. Demographers use a diversity index to measure the probability that two randomly selected individuals belong to different racial or ethnic groups. In St. Martin County, that probability was 50.9% in 2020 and 51.8% in the most recent ACS estimates.

St. Martin County is ranked the 21st most populous county in Louisiana, out of 64 counties. St. Martin County was ranked the 21st most populous county in the 2020 Census.

St. Martin County's White Population

32,398 residents of St. Martin County, or 63.1% of the population, identify as White. The share of White residents in St. Martin County is higher than in Louisiana overall, where 55.7% of the population is White. St. Martin County ranks 23rd statewide in terms of White residents as a share of the population, out of 64 counties.

Since the 2020 Census, St. Martin County's White population has declined by an estimated 1.6%. White residents' share of St. Martin County's population has decreased from 63.6% to 63.1%.

St. Martin County is more White than neighboring Iberville County (46% White), Iberia County (56% White), West Baton Rouge County (52.2% White), Lafayette County (61.7% White), and St. Mary County (53.4% White).

St. Martin County's Black Population

14,690 residents of St. Martin County, or 28.6% of the population, identify as Black. The share of Black residents in St. Martin County is comparable to the share in Louisiana overall, where 30.5% of the population is Black. St. Martin County ranks 31st statewide in terms of Black residents as a share of the population, out of 64 counties.

Since the 2020 Census, St. Martin County's Black population has declined by an estimated 2.4%. Black residents' share of St. Martin County's population has decreased from 29.1% to 28.6%.

St. Martin County is more Black than neighboring Lafayette County (25.4% Black). St. Martin County is less Black than neighboring Iberville County (43.2% Black), Iberia County (31% Black), West Baton Rouge County (40.8% Black), and St. Mary County (28.8% Black).

St. Martin County's Asian Population

390 residents of St. Martin County, or 0.8% of the population, identify as Asian. The share of Asian residents in St. Martin County is comparable to the share in Louisiana overall, where 1.7% of the population is Asian. St. Martin County ranks 25th statewide in terms of Asian residents as a share of the population, out of 64 counties.

Since the 2020 Census, St. Martin County's Asian population has declined by an estimated 11.4%. Asian residents' share of St. Martin County's population has remained roughly unchanged at 0.8%.

St. Martin County is more Asian than neighboring Iberville County (0% Asian), and West Baton Rouge County (0.5% Asian). St. Martin County is less Asian than neighboring Iberia County (2.5% Asian), Lafayette County (1.9% Asian), and St. Mary County (1% Asian).

St. Martin County's Hispanic Population

1,873 residents of St. Martin County, or 3.6% of the population, identify as Hispanic. The share of Hispanic residents in St. Martin County is slightly lower than in Louisiana overall, where 7.2% of the population is Hispanic. St. Martin County ranks 42nd statewide in terms of Hispanic residents as a share of the population, out of 64 counties.

Since the 2020 Census, St. Martin County's Hispanic population has grown by an estimated 11.6%. Hispanic residents' share of St. Martin County's population has remained roughly unchanged at 3.6%.

St. Martin County is less Hispanic than neighboring Iberville County (5.2% Hispanic), Iberia County (5.6% Hispanic), West Baton Rouge County (4.6% Hispanic), Lafayette County (6.7% Hispanic), and St. Mary County (9.8% Hispanic).

St. Martin County's Native American/Other Population

302 residents of St. Martin County, or 0.6% of the population, identify as American Indian/Alaska Native/Native Hawaiian/Pacific Islander/Other. The share of Native American/Other residents in St. Martin County is comparable to the share in Louisiana overall, where 1% of the population is Native American/Other. St. Martin County ranks 29th statewide in terms of Native American/Other residents as a share of the population, out of 64 counties.

Since the 2020 Census, St. Martin County's Native American/Other population has declined by an estimated 13.7%. Native American/Other residents' share of St. Martin County's population has remained roughly unchanged at 0.6%.

St. Martin County is more Native American/Other than neighboring West Baton Rouge County (0.1% Native American/Other). St. Martin County is less Native American/Other than neighboring Iberville County (0.9% Native American/Other), Iberia County (0.8% Native American/Other), and St. Mary County (1.8% Native American/Other).

St. Martin County's Multiracial Population

1,700 residents of St. Martin County, or 3.3% of the population, identify as Multiracial. The share of Multiracial residents in St. Martin County is comparable to the share in Louisiana overall, where 3.8% of the population is Multiracial. St. Martin County ranks 46th statewide in terms of Multiracial residents as a share of the population, out of 64 counties.

Since the 2020 Census, St. Martin County's Multiracial population has grown by an estimated 27.9%. Multiracial residents' share of St. Martin County's population has increased from 2.6% to 3.3%.

St. Martin County is more Multiracial than neighboring West Baton Rouge County (1.7% Multiracial). St. Martin County is less Multiracial than neighboring Iberville County (4.6% Multiracial), Iberia County (4.1% Multiracial), Lafayette County (3.6% Multiracial), and St. Mary County (5.2% 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.