The Lankester sailed to New Orleans from Madagascar every year up until its sinking in 1901. The Sixth Doctor and Peri Brown took a trip aboard the Lankester to journey to New Orleans. (AUDIO: Cryptobiosis)
Though it's possible that a real world location doesn't exist in the same geographic space in the Doctor Who universe, such cases are few and far between. Thus, the map at right is probably a good indicator of the DWU location of New Orleans.