The Omaha Zoo Railroad (OZRR) is the name of the narrow gauge steam train that carries visitors around the Henry Doorly Zoo in Omaha, Nebraska. The train loads passengers at two stations within the world-class zoo, and also makes a stop at the zoo's Pachyderm Hill exhibit, where guests can exit and re-board at a later time. Trains operate daily from Memorial Day to Labor Day, and on weekends in April, May, September and October weather permitting. The last train each day generally leaves 1 hour before zoo gates close, but hours are often extended due to crowds. Zoo admission or membership is required to enter the zoo, and there is an additional fee to ride the train. Annual ridership of the Omaha Zoo Railroad is over 200,000 people.