When the Bureau of Land Management (blm) was formed in 1946, the agency and the lands it managed had an ambiguous identity and future. Formed by President Truman through the merger of the General Land Office and the U.S. Grazing Service, the blm inherited the remaining 450 million acres of public-domain lands in the American West and Alaska, which I will refer to simply as “the public lands.” With those lands, the blm also inherited a set of property-rights regimes—that is, a set of property rights, privileges, and relationships that control land and resource access, withdrawal, management, exclusion, and alienation—that were strongly reflective of the nineteenth-century frontier era. They were marked by private initiative, self-regulation by public lands users, and common-law principles of prior use and appropriation. Indeed, public lands users often acted as if they held common-law rights to the public lands, claims that western congressmen defended through appropriations and oversight.