Although cotton dominated the economy of Cameron during the 19th century, the 20th century brought more diversified industries. The discovery of oil in neighboring Williamson County in 1915 prompted Milam County residents to initiate their own exploration. The Minerva-Rockdale oil field, discovered in 1921, provided new opportunities for investment. In the 1920s and 1930s, several milk-product companies also operated in Cameron, including the Kraft-Phenix Cheese Corporation. At the 1930 census, the population was 4,565. That figure rose to 5,040 in 1940.
