ADEX

Rex 84, short for Readiness Exercise 1984, was a plan by the United States federal government to test their ability to detain large numbers of American citizens in case of massive civil unrest or national emergency. Exercises similar to Rex 84 happen periodically. Plans for roundups of persons in the United States in times of crisis are constructed during periods of increased political repression such as the Palmer Raids and the McCarthy Era. For example, from 1967 to 1971 the FBI kept a list of persons to be rounded up as subversive, dubbed the "ADEX" list.
See more at Wikipedia.org...