Plymouth County Demographics

A map of Plymouth County's Population by Race

Race	2024 Pop	2020 Pop	2024 %	2020 %
White	22,664	22,941	88.0%	89.3%
Hispanic	1,653	1,496	6.4%	5.8%
Black	615	354	2.4%	1.4%
Multiracial	504	577	2.0%	2.2%
Native American/Other	176	219	0.7%	0.9%
Asian	135	111	0.5%	0.4%

Plymouth County, Iowa has an estimated population of 25,747, a less than 1% change from the 25,698 recorded in the 2020 Census. The population is 88.0% White, 6.4% Hispanic, 2.4% Black, 2.0% Multiracial, 0.7% Native American/Other, and 0.5% Asian. This demographic dot map shows the population of Plymouth County, with one dot drawn for each person counted by the Census, color-coded by race.

Plymouth has become more racially diverse since the 2020 Census. It is considerably less diverse than Iowa overall. Demographers use a diversity index to measure the probability that two randomly selected individuals belong to different racial or ethnic groups. In Plymouth County, that probability was 19.9% in 2020 and 22.0% in the most recent ACS estimates.

Plymouth County is ranked the 24th most populous county in Iowa, out of 99 counties. Plymouth County was ranked the 24th most populous county in the 2020 Census.

Plymouth County's White Population

22,664 residents of Plymouth County, or 88.0% of the population, identify as White. The share of White residents in Plymouth County is higher than in Iowa overall, where 82.3% of the population is White. Plymouth County ranks 63rd statewide in terms of White residents as a share of the population, out of 99 counties.

Since the 2020 Census, Plymouth County's White population has declined by an estimated 1.2%. White residents' share of Plymouth County's population has decreased from 89.3% to 88.0%.

Plymouth County is more White than neighboring Sioux County (82.8% White), Woodbury County (67.1% White), and Dakota County (42.3% White). Plymouth County is less White than neighboring Union County (88.4% White), and Cherokee County (88.6% White).

Plymouth County's Black Population

615 residents of Plymouth County, or 2.4% of the population, identify as Black. The share of Black residents in Plymouth County is comparable to the share in Iowa overall, where 3.8% of the population is Black. Plymouth County ranks 31st statewide in terms of Black residents as a share of the population, out of 99 counties.

Since the 2020 Census, Plymouth County's Black population has grown by an estimated 73.7%. Black residents' share of Plymouth County's population has increased from 1.4% to 2.4%.

Plymouth County is more Black than neighboring Sioux County (0.6% Black), Union County (0.9% Black), and Cherokee County (1% Black). Plymouth County is less Black than neighboring Woodbury County (4.9% Black), and Dakota County (8.7% Black).

Plymouth County's Asian Population

135 residents of Plymouth County, or 0.5% of the population, identify as Asian. The share of Asian residents in Plymouth County is comparable to the share in Iowa overall, where 2.5% of the population is Asian. Plymouth County ranks 52nd statewide in terms of Asian residents as a share of the population, out of 99 counties.

Since the 2020 Census, Plymouth County's Asian population has grown by an estimated 21.6%. Asian residents' share of Plymouth County's population has remained roughly unchanged at 0.5%.

Plymouth County is more Asian than neighboring Cherokee County (0.4% Asian). Plymouth County is less Asian than neighboring Woodbury County (2.3% Asian), Union County (1.1% Asian), and Dakota County (3% Asian).

Plymouth County's Hispanic Population

1,653 residents of Plymouth County, or 6.4% of the population, identify as Hispanic. The share of Hispanic residents in Plymouth County is comparable to the share in Iowa overall, where 7.3% of the population is Hispanic. Plymouth County ranks 25th statewide in terms of Hispanic residents as a share of the population, out of 99 counties.

Since the 2020 Census, Plymouth County's Hispanic population has grown by an estimated 10.5%. Hispanic residents' share of Plymouth County's population has increased from 5.8% to 6.4%.

Plymouth County is more Hispanic than neighboring Union County (4.8% Hispanic), and Cherokee County (5.4% Hispanic). Plymouth County is less Hispanic than neighboring Sioux County (14.3% Hispanic), Woodbury County (19.1% Hispanic), and Dakota County (41.6% Hispanic).

Plymouth County's Native American/Other Population

176 residents of Plymouth County, or 0.7% of the population, identify as American Indian/Alaska Native/Native Hawaiian/Pacific Islander/Other. The share of Native American/Other residents in Plymouth County is comparable to the share in Iowa overall, where 0.6% of the population is Native American/Other. Plymouth County ranks 12th statewide in terms of Native American/Other residents as a share of the population, out of 99 counties.

Since the 2020 Census, Plymouth County's Native American/Other population has declined by an estimated 19.6%. Native American/Other residents' share of Plymouth County's population has remained roughly unchanged at 0.7%.

Plymouth County is more Native American/Other than neighboring Sioux County (0.4% Native American/Other), and Cherokee County (0.2% Native American/Other). Plymouth County is less Native American/Other than neighboring Woodbury County (2.3% Native American/Other), Union County (1% Native American/Other), and Dakota County (2.1% Native American/Other).

Plymouth County's Multiracial Population

504 residents of Plymouth County, or 2.0% of the population, identify as Multiracial. The share of Multiracial residents in Plymouth County is comparable to the share in Iowa overall, where 3.5% of the population is Multiracial. Plymouth County ranks 67th statewide in terms of Multiracial residents as a share of the population, out of 99 counties.

Since the 2020 Census, Plymouth County's Multiracial population has declined by an estimated 12.7%. Multiracial residents' share of Plymouth County's population has remained roughly unchanged at 2.0%.

Plymouth County is more Multiracial than neighboring Sioux County (1.3% Multiracial). Plymouth County is less Multiracial than neighboring Woodbury County (4.3% Multiracial), Union County (3.7% Multiracial), Dakota County (2.3% Multiracial), and Cherokee County (4.5% 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.