Rupert Mason was a leading financier of irrigation districts in California and was active in the purchase and distribution of municipal bonds in the state after 1907. Mason began his work with municipal bonds in Chicago with the company N.W. Harris & Co. before moving to their California office. While there, he created his own firm, J.R. Mason & Company in San Francisco, which specialized in irrigation district bonds until Mason's retirement in 1927. During his time at Mason & Co. he worked on land assessment versus water toll payments, public versus private power distribution, and financing water development districts. He returned to the irrigation business in 1934 after the Federal Municipal Bankruptcy Act was passed. Mason attempted to prove that this act was unconstitutional, destructive of the good credit of the irrigation districts, and unfair to the purchasers of bonds. He was also a leader in the Single-Tax movement both in the United States and abroad. In this interview, Mason discusses the Irrigation District Act of 1897 and its amendments, the District Securities Commission (1913), bondholder's protective committees, his leadership in the Single-Tax movement, the Boulder Canyon Project, the Raker Act, tidelands oil, and other land issues.