Seasonal factors for auto and truck production were revised back to January 1996 and extended through June 2018 on March 17, 2017. The revised factors for September 2016 through February 2017 were used in the G.17 release published on March 17, 2017, and the revised factors for earlier months will be incorporated into the production estimates at the time of the annual revision on March 31, 2017. The revised seasonal factors are based on production data through January 2017. The revised factors also correct an error in the number of holidays for January 2017, which had previously been understated. The seasonal factors will be revised again in March 2018.