Go here to view a slide show on the evolution of Paricutin prepared by Scott Rowland. Sources of Information: Foshag, W.F., and Gonzalez-Reyna, J., 1956, Birth and development of Paricutin volcano: U.S. Geological Survey Bulletin 965-D, p. 355-489.
In 1971, the Twenty-sixth Amendment set the legal voting age at 18 for both US federal and state elections.
Until 1972, the voting age in the United States was 21 years. The  26th Amendment reduced the voting age to 18 years old.