Atchafalaya Basin: Size, Location & Significance - The Largest Swamp in the US
The Atchafalaya Basin, which includes the Atchafalaya Swamp, is approximately 600,000 acres (243,000 hectares).
It's important to note that the term "Atchafalaya Swamp" can be used loosely to refer to the whole basin, or just specific areas within it. The basin itself is the largest swamp in the United States.
