The system was sold in 1944 by Huntington's estate to American City Lines, Inc., of Chicago, a subsidiary of National City Lines, a holding company that was purchasing transit systems across the country. The sale was announced December 5, 1944, but the purchase price was not disclosed. National City Lines, along with its investors that included Firestone Tire, Standard Oil of California (now Chevron Corporation) and General Motors, were later convicted of conspiring to monopolize the sale of buses and related products to local transit companies controlled by National City Lines and other companies in what became known as the General Motors streetcar conspiracy. National City Lines purchased Key System, which operated streetcars systems in Northern California, the following year.