The helium resources base of the United States was estimated by the Bureau of Mines to be 961 bcf as of January 1, 1983. These resources are divided into four categories in decresing degree of assurance of their existence: (1) helium in storage and in proved natural gas reserves, 271 bcf, (2) helium in probable natural gas resources, estimated at 202 bcf, (3) helium in possible natural gas resources, estimated to be 351 bcf, and (4) helium in speculative natural gas resources, which makes up the remaining 137 bcf. These helium resources are further divided into depleting, nondepleting, and stored classifications. The depleting resources are those associated with natural gas fields that are, or will be, produced for the natural gas they contain. All of the helium in potential (probable, possible, and speculative) natural gas resources is included in this classification. These depleting resources are estimated to contain 789 bcf of the total helium resource base. Helium resources contained in nondepleting natural gas resources, those in shut-in, abandoned, or otherwise nonproducing natural gas fields, are estimated to total 134 bcf. There is 38 bcf of helium in storage in the federal government-owned Cliffside gas field near Amarillo, Texas.