Note: Do not rely on this information. It is very old.
Preemption
Pre-emption. The Pre-emption Act, which came into force in the United States in 1841, confers on any person who has settled on a piece of public land a prior claim to obtain the same by purchase, provided that it does not exceed 160 acres. The price is uniform in all cases. Title to land is acquired more speedily in this manner than by means of the Homestead Laws.