[4] Donaldsonville's historic district has what has been described as the finest collection of buildings from the antebellum era to 1933, of any of the Louisiana river towns above New Orleans.

[7] They developed agriculture in the parish, mainly as sugar cane plantations worked by African slave labor.

Acadians, expelled by the British from Acadia in 1755, began to settle in the area from 1756 to 1785, where they developed small subsistence farms.

Landowner and planter William Donaldson in 1806 commissioned the architect and planner, Barthelemy Lafon, to plan a new town at this site.

As a result of the wealth planters gained from sugar and cotton commodity crops, they built fine mansions and other buildings in town during the antebellum years.

Historian John D. Winters, in his The Civil War in Louisiana (1963), describes the scene: The irate naval commander, Admiral Farragut, ordered the bombardment of Donaldsonville as soon as it could be evacuated.

A citizens' committee met and decided to ask Governor Moore to keep the [Confederate] Rangers from firing on Federal boats.

These attacks did no real good and brought only crude reprisals against the innocent and helped to keep the Negroes stirred up.

[12]A citizen complained that the Rangers were useless and lawless, unable or unwilling to protect Confederate property.

The citizen added that the Confederate people "could not fare worse were we surrounded by a band of Lincoln's mercenary hirelings.

They stayed and worked with Union forces, helping build the star-shaped Fort Butler in the town.

Free blacks and fugitive slaves joined in the successful defense of the fort, in one of the first times they fought as soldiers on behalf of the Union.

"[14] Historian Don Frazier, wrote; "Not only did black hands build this citadel of freedom, they defended it to the death.

In 1868 the city elected the first African-American mayor in the United States, Pierre Caliste Landry,[6] a former slave who been educated in schools on a plantation owned by the Bringier family.

This was the period of the Great Migration, when tens of thousands of African Americans left the rural South to go for opportunities in northern and midwestern cities.

[citation needed] Historian Sidney A. Marchand, who was also an attorney, was elected as mayor of the city and state legislator during that period.

Today the Donaldsonville Historic District has what is described as the "finest collection of buildings from the pre-Civil War to 1933 period" of rivertowns above New Orleans.

[19] According to the United States Census Bureau, the city has a total area of 2.5 square miles (6.5 km2), all land.

Coming upriver on the Mississippi, Donaldsonville is the point of the first expanse of land beyond the narrow natural levee.

Donaldsonville is located where Bayou Lafourche, a distributary of the Mississippi River, formerly branched off until the entrance was dammed in 1905.