In 1981, Fermilab director Leon M. Lederman asked for preliminary proposals for a "modest detector built by a modestly sized group" that would be located at the 'DØ' interaction region in the Tevatron ring and complement the planned Collider Detector at Fermilab. More than fifteen groups submitted proposals. Three of these proposals were merged into one effort under the leadership of Paul Grannis, which officially began on July 1, 1983. The group produced a design report in November 1984. The detector was completed in 1991, it was placed in the Tevatron in February 1992, and observed its first collision in May 1992. It recorded data from 1992 until 1996, when it was shut down for major upgrades. Its second run began in 2001 and lasted until September 2011. As of 2019, data analysis is still going on.