|It not really known how many bison were alive before Europeans arrived as there were no accurate counts, but scientists estimate the herds to have been between thirty and sixty million. Decimation of the bison started with disease from domesticated animals and then the unchecked slaughter of bison in the last half of the 18th century. As people moved west the bison populations declined until there were no bison left east of the Mississippi and as people headed to the new frontier further west the populations were decimated. Bison were considered undesirable because of their wild tendencies and their awesome power. What could have turned into another dodo bird, instead became a success story due to several individuals who made an effort to preserve and protect the remaining animals. Many of the remaining animals left in the wild were collected and put on either private ranches, zoos or on preserves. Many of those preserves have turn into national or state parks where the public can view bison. Bison are making a comeback on private ranches and on reservations across North America. There are twice as many buffalo today then there was just twenty years ago.