Spirit Airlines will launch six new routes on 9 November.
It will offer nonstop service to New Orleans from Boston, Newark, Tampa and Minneapolis/St Paul. Spirit will operate daily on all the routes, with the exception of Minneapolis/St Paul, which it will fly from four-times weekly.
Separately, Spirit will add daily service between Newark and Las Vegas, and between Chicago O'Hare and West Palm Beach. Spirit will operate seasonally on the West Palm Beach route until 11 April 2018.
Spirit will compete against JetBlue Airways on New Orleans-Boston, United Airlines on New Orleans-Newark, Southwest Airlines on New Orleans-Tampa and Delta Air Lines on New Orleans-Minneapolis/St Paul, FlightGlobal schedules data show.
Delta had also previously announced plans to begin seasonal flights between New Orleans and Boston from 10 February 2018 to 1 April 2018.
Spirit will compete against United on Newark-Las Vegas, and American Airlines on Chicago O'Hare-West Palm Beach.
Florida-based Spirit will also face indirect competition on some of the new routes. Delta and JetBlue fly to New Orleans from New York John F Kennedy, and Delta also serves New Orleans from LaGuardia.
Delta, JetBlue, American and Virgin America all operate between Las Vegas and New York JFK.