According to Wikipedia, "ACT (originally an abbreviation of American College Testing) is a standardized test for high school achievement and college admissions in the United States produced by ACT, Inc. It was first administered in November 1959 by Everett Franklin Lindquist as a competitor to the College Board's Scholastic Aptitude Test, now the SAT Reasoning Test. The ACT has historically consisted of four tests: English, Mathematics, Reading, and Science Reasoning. In February 2005, an optional Writing test was added to the ACT, mirroring changes to the SAT that took place later in March of the same year."
Mississippi Department of Education, Office of Research and Statistics, ACT for [Year] Graduating Seniors.
Available at: http://reports.mde.k12.ms.us/data/
Updated January 2014.