By 1975, there were only 324 known nesting pairs of American peregrine falcons in the United States.
It is estimated that prior to the 1940s, there were approximately 3,875 nesting pairs of peregrines in North America. From the 1940s through the 1960s the total population dropped dramatically, due in large part to the introduction of synthetic pesticides to the environment. By 1975, there were only 324 known nesting pairs of American peregrine falcons in the United States. This incredibly fast hunter was listed as endangered in 1970 but has made a remarkable recovery due to the banning of the pesticide DDT and conservation efforts. It was removed from the list of endangered species in 1999. The recovery of the peregrine falcon demonstrates the importance of reducing threats and promoting conservation efforts to promote species recovery.