Rusticated concrete block, also called rockfaced concrete block, was made in a mold to create a surface texture that resembles stone. Its popularity as a building material peaked between 1905 and 1930. Concrete and concrete block were popular building materials well before then, but it took two technological advances to make mass production of rusticated concrete block possible.

First, Harmon S. Palmer patented a hollow concrete block manufacturing machine. Second, the method of making Portland cement was improved and standardized. With a easy manufacturing method and reliable materials, rusticated concrete block became a widely popular building material, the ideal being that with nonskilled labor, the blocks could be made at the construction site. Block machines were even sold through the Sears catalog. Advantages of the blocks included that they were less expensive to lay than brick, they imitated the appearance of a more expensive material (quarried stone), and they were fire resistant.

In 1917, F. J. Straub patented a method of making cinder blocks. Cinder blocks used aggregates to make a lighter block, and they had smooth surfaces rather than the rough surface of rock-faced blocks. By the 1930s, cinderblock had replaced rusticated concrete blocks in popularity as a building material.

Sources:

"Historic of the Historic Largo Feed Store," pamphlet produced by the Largo Historical Society, Largo, Florida.

Pamela H. Simpson, "Cheap, Quick, and Easy: The Early History of Rockfaced Concrete Block Building," Perspectives in Vernacular Architecture, 1989.