Passenger Pigeons (Ectopistes migratorius) were once the most abundant bird in North America, with flock sizes estimated in the billions. However, by the turn of the 20th century, this previously abundant species had been driven to extinction. Morphological analyses linked the Passenger Pigeon with the New World mourning doves of the genus Zenaida. However, mitochondrial analyses strongly support its placement within the group of typical pigeons and doves (New and Old World pigeons, cuckoo-doves, turtledoves). Here, the first nuclear DNA sequence obtained for this extinct species confirms the placement of the Passenger Pigeon as sister to the New World pigeons, Patagioenas. These findings have implications for the colonization of North America by pigeons and doves.