Assumption Parish (French: Paroisse de l'Assomption, Spanish: Parroquia de la Asunción) is a parish located in the U.S. state of Louisiana. As of the 2020 census, the population was 21,039. Its parish seat is Napoleonville. Assumption Parish was established in 1807, as one of the original parishes of the Territory of Orleans.

Assumption Parish is one of the twenty-two Acadiana parishes. Its major product is sugar cane. In proportion to its area, Assumption Parish produces the most sugar of any parish of Louisiana.

In 1807, Assumption became the eighth parish of the Orleans Territory. Its history is rooted in its waterways and its large expanse of fertile soils ideal for farming. Settled in the middle 18th century by French and Spanish settlers, the area retains strong cultural ties to its past with conversational French still common among residents. Assumption was also a final destination for many of the French Acadians exiled from Nova Scotia between 1755 and 1764.

According to the U.S. Census Bureau, the parish has a total area of 365 square miles (950 km), of which 339 square miles (880 km) is land and 26 square miles (67 km) (7.1%) is water.

• Future Interstate 49
• U.S. Highway 90
• Louisiana Highway 1
• Louisiana Highway 70
• Louisiana Highway 182
• Louisiana Highway 308

• Napoleonville (parish seat and only municipality)

• Bayou Corne
• Bayou L'Ourse
• Belle Rose
• Labadieville
• Paincourtville
• Pierre Part
• Supreme

• Albemarle
• Belle Alliance
• Belle River
• Bruly St. Martin
• Cancienne
• Foley
• Klotzville
• Plattenville
• Westfield
• Wildwood
• Woodlawn

Historical population

Census	Pop.	Note	%±
1810	2,472		—
1820	3,576		44.7%
1830	5,669		58.5%
1840	7,141		26.0%
1850	10,538		47.6%
1860	15,379		45.9%
1870	13,234		−13.9%
1880	17,010		28.5%
1890	19,629		15.4%
1900	21,620		10.1%
1910	24,128		11.6%
1920	17,912		−25.8%
1930	15,990		−10.7%
1940	18,541		16.0%
1950	17,278		−6.8%
1960	17,991		4.1%
1970	19,654		9.2%
1980	22,084		12.4%
1990	22,753		3.0%
2000	23,388		2.8%
2010	23,421		0.1%
2020	21,039		−10.2%
U.S. Decennial Census 1790-1960 1900-1990 1990-2000 2010

Assumption Parish racial composition as of 2020

Race	Number	Percentage
White (non-Hispanic)	13,580	64.55%
Black or African American (non-Hispanic)	5,973	28.39%
Native American	83	0.39%
Asian	56	0.27%
Other/Mixed	433	2.06%
Hispanic or Latino	914	4.34%

As of the 2020 United States census, there were 21,039 people, 8,552 households, and 5,484 families residing in the parish. During the 2010 United States census, there were 23,421 people living in the parish. Among its 2010 population, 66.8% were White, 30.5% Black or African American, 0.6% Native American, 0.2% Asian, 0.1% Pacific Islander, 1.0% of some other race and 0.9% of two or more races. 2.1% were Hispanic or Latino (of any race). 38.2% were of French, French Canadian or Cajun and 9.4% American ancestry.

The Assumption Parish School Board operates local public schools. Assumption High School serves the whole parish. There is one private school in the parish, Saint Elizabeth School, which was founded in 1834.

• Assumption High School
• Bayou L'Ourse Primary School
• Belle Rose Middle School
• Belle Rose Primary School
• Labadieville Middle School
• Labadieville Primary School
• Napoleonville Middle School
• Napoleonville Primary School
• Pierre Part Elementary School
• Saint Elizabeth School

The 928th Sapper Company, a unit of the 769th Engineer Battalion and the 225th Engineer Brigade.

Assumption Parish is represented in the Louisiana House of Representatives by Beryl Amedee, a Republican, and Chad Brown, a Democrat. During the "Solid South" era, conflicts over trade policy often caused Assumption Parish to deviate somewhat from overwhelming Democratic support, as did rebellion in the Acadiana region against Woodrow Wilson's perceived hostility towards France.

Since the Dixiecrat revolt, by contrast, Assumption has been a typical rural South Louisiana parish in its political behaviour. It backed Dixiecrat Strom Thurmond in 1948 and Dwight D. Eisenhower in 1956 before showing powerful pro-Catholic behaviour in 1960 and then turning powerfully against liberal Midwestern Democrats in 1968 and 1972. With the nomination of the more centrist Southerner Jimmy Carter in 1976, Assumption became again Democratic leaning until the 2000s, when, like all of the rural white South, it has turned powerfully Republican due to disagreements with the Democratic Party's liberal views on social issues.

United States presidential election results for Assumption Parish, Louisiana

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2020	7,271	64.72%	3,833	34.12%	131	1.17%
2016	6,714	61.57%	3,931	36.05%	259	2.38%
2012	6,083	55.34%	4,754	43.25%	155	1.41%
2008	5,981	54.57%	4,756	43.39%	223	2.03%
2004	4,966	46.26%	5,585	52.03%	184	1.71%
2000	4,388	43.65%	5,222	51.94%	443	4.41%
1996	2,698	26.42%	6,416	62.83%	1,098	10.75%
1992	2,928	28.01%	5,639	53.95%	1,886	18.04%
1988	4,017	40.19%	5,610	56.13%	368	3.68%
1984	5,433	52.43%	4,660	44.97%	270	2.61%
1980	4,001	44.10%	4,679	51.57%	393	4.33%
1976	3,117	40.42%	4,401	57.07%	193	2.50%
1972	3,751	58.93%	2,065	32.44%	549	8.63%
1968	1,222	19.69%	2,085	33.60%	2,898	46.70%
1964	2,112	40.87%	3,056	59.13%	0	0.00%
1960	766	18.19%	3,019	71.69%	426	10.12%
1956	1,708	55.17%	1,282	41.41%	106	3.42%
1952	1,210	42.35%	1,647	57.65%	0	0.00%
1948	469	25.57%	362	19.74%	1,003	54.69%
1944	426	23.09%	1,419	76.91%	0	0.00%
1940	722	29.10%	1,759	70.90%	0	0.00%
1936	1,111	60.94%	712	39.06%	0	0.00%
1932	386	20.06%	1,538	79.94%	0	0.00%
1928	307	24.46%	948	75.54%	0	0.00%
1924	601	66.34%	305	33.66%	0	0.00%
1920	725	78.21%	202	21.79%	0	0.00%
1916	221	20.41%	489	45.15%	373	34.44%
1912	149	20.03%	423	56.85%	172	23.12%

• Kim Willoughby, American indoor volleyball player, 2008 U.S. volleyball Olympian, former University of Hawaii volleyball player, 2003 AVCA NCAA National Player of the Year
• Charles Melançon, former Democratic member of the United States House of Representatives
• Troy E. Brown, a former member of the Louisiana State Senate
• Brandon Jacobs, two-time Super bowl winner, former running back for the New York Giants
• Johnny Meads, is a former professional American football linebacker in the National Football League Houston Oilers Washington Redskins
• J. E. Jumonville Sr., was a businessman, farmer, and horse breeder born in Paincourtville state senator
• Samuel A. LeBlanc I, was a lawyer from Napoleonville born in Paincourtville in Assumption Parish
• Whitmell P. Martin, was a U.S. Representative from Assumption Parish Louisiana from 1915 to 1929.

• Bayou Corne sinkhole
• National Register of Historic Places listings in Assumption Parish, Louisiana
• Isleños in Louisiana#Valenzuela
• Troy E. Brown
• Samuel A. LeBlanc I
• J. E. Jumonville Sr.

29°54′N 91°04′W / 29.90°N 91.06°W / 29.90; -91.06