路易斯安那购地（英语：Louisiana Purchase；法语：Vente de la Louisiane）是美国于1803年以大约每英亩三美分向法国购买超过529,911,680英亩（2,144,476平方公里）土地的交易案，该交易的总价为1500万美元或相当于8000万法郎；如以国内生产总值相对比例计算，此数在2004年相当4178亿美元。

法属路易斯安那的版图比今日美国的路易斯安那州大很多。从南至北，该属地范围包括了现今美国路易斯安那州密西西比河两岸（包括新奥尔良市）、阿肯色州、奥克拉荷马州、德克萨斯州北部边界地带、新墨西哥州东北角、密苏里州、堪萨斯州、科罗拉多州洛基山脉以东、爱荷华州、内布拉斯加州、怀俄明州大部（落基山脉以东）、明尼苏达州密西西比河以西、南达科他州、北达科他州大部、蒙大拿州大部（除西端），以及现今加拿大马尼托巴、萨斯喀彻温、艾伯塔各省之密苏里河流域地区（也即南部边境地带）。

The Louisiana Purchase (French:Vente de la Louisiane "Sale of Louisiana") was the acquisition of the Louisiana territory (828,000 square miles) by the United States from France in 1803. The U.S. paid fifty million francs ($11,250,000 USD) and a cancellation of debts worth eighteen million francs ($3,750,000 USD) for a total of sixty-eight million francs ($15,000,000 USD). The Louisiana territory included land from fifteen present U.S. states and two Canadian provinces. The territory contained land that forms Arkansas, Missouri, Iowa, Oklahoma, Kansas, and Nebraska; the portion of Minnesota west of the Mississippi River; a large portion of North Dakota; a large portion of South Dakota; the northeastern section of New Mexico; the northern portion of Texas; the area of Montana, Wyoming, and Colorado east of the Continental Divide; Louisiana west of the Mississippi River (plus New Orleans); and small portions of land within the present Canadian provinces of Alberta and Saskatchewan. Its population was around 60,000 inhabitants, of whom half were African slaves.