The first donkeys came to the Americas on ships of the Second Voyage of Christopher Columbus, and were landed at Hispaniola in 1495. The first to reach North America may have been two animals taken to Mexico by Juan de Zumárraga, the first bishop of Mexico, who arrived there on 6 December 1528, while the first donkeys to reach what is now the United States may have crossed the Rio Grande with Juan de Oñate in April 1598. From that time on they spread northward, finding use in missions and mines. Donkeys were documented as present in what today is Arizona in 1679. By the Gold Rush years of the 19th century, the burro was the beast of burden of choice of early prospectors in the western United States. With the end of the placer mining boom, many of them escaped or were abandoned, and a feral population established itself.