The study began in 2005, but was put on hold in 2007 due to the economic recession. In 2013, ADOT and the Federal Highway Administration (FHWA) reinitiated the study of Loop 303 south of Van Buren Street to SR 30. Construction of Loop 303 south, between I-10 and Van Buren Street, began in February 2016 and was completed in October 2017. The next segment of Loop 303, Van Buren Street to MC 85, is scheduled to begin final design in the Winter 2018 and begin construction Fall 2020, pending Finding of No Significant Impact (FONSI).
Throughout its length, Loop 303 has been planned to accommodate an ultimate configuration of four general-purpose lanes and one high-occupancy vehicle (carpool) lane in each direction.