We documented single Short-tailed Hawks (Buteo brachyurus) in the states of Chihuahua in April 2005 and New Mexico in May and June 2005. These are the first reports for both states. To put these records into historical and geographical context, we compiled published reports for western Mexico and Arizona and for northeastern Mexico and Texas; these indicate a steady northward range expansion by this species over the past half century, an expansion that may have accelerated in recent years.