The timing of births in ungulates has significant implications for juvenile survival and population growth. For North American elk (Cervus elaphus), typical parturition season ranges from late May to early Jun., and juveniles born outside of this peak characteristically exhibit lowered survival. We observed abnormally long parturition seasons in free-ranging elk populations in Missouri and South Dakota during 2012. Both populations exhibited late births; the last known births occurred on 26 Sep. in Missouri and 4 Sep. in South Dakota. Duration of parturition season was 112 and 119 d in Missouri and South Dakota, respectively. In Missouri, late births likely resulted from breeding by both yearling females and males. Late parturition in South Dakota may be caused by extended estrous cycles of elk that occurred on high quality range where few adult males were located.