In the 1930's, the Chrysler Corporation introduced the Chrysler Airflow, featuring an advanced streamlined body which was among the first to be designed according to scientific aerodynamic principles. Chrysler also created the industry's first wind tunnel to develop them. Unfortunately, it wasn't accepted well by the public, and it was the humble Dodge and Plymouth divisions, which had not been given an Airflow model, which pulled the firm through the Depression years with its conventional but quite popular body styles.
Plymouth was one of only a few marques that actually increased sales during the cash-strapped thirties. It was during this decade that the company created a formal parts division under the Mopar (Motor Parts) brand, with the result that Chrysler products are still often called Mopars.
By the end of the 1930's, the DeSoto and Dodge divisions would flip-flop spots in the corporate pecking order making the lineup Plymouth, Dodge, DeSoto, Chrysler, and Imperial.