The Osage Oilfield was the first large producing oil field in Weston County. The first oil well drilled there and put into commercial production was a discovery well drilled by the Sinclair Oil Company in 1919, then immediately sold to Alliance Oil Company, and it produced most of the county's oil until the end of World War II. Oil came from shallow wells drilled into the Lower Cretaceous age Muddy Sandstone Member of the Thermopolis Formation at depths ranging from a few hundred feet to more than a thousand feet. The oil was a light grade, and a high percentage of it could be refined into gasoline. The field went through several phases of extraction using primary and secondary recovery methods, and an organized water flood technique began operating in the late 1950s and early 1960s. The Osage oil boom brought many workers and fortune seekers into Weston County in the early part of the 20th century. The field produced many skilled oilfield workers, helping Weston County develop other producing fields, while oil from more remote county locations was refined locally and sent to other markets by railcars and pipeline. During the Great Depression of the 1930s, when the county government could not collect property taxes from local businesses, individuals, and ranches, mineral taxes from Osage field production provided a reliable source of county income. Other oilfields in the county were developed after World War II, and the Osage Oilfield remains in production.