Because of the growth of Florida tourism in the 1930s, the Atlantic Coast Line was experiencing a surge in its passenger business. To handle this heavy traffic, many of the main line trains were powered by 4-6-2 Pacifics pulling no more than 12 to 14 cars.

In 1937, the ACL received 12 new Class R-1 4-8-4s from the Baldwin Locomotive Works. They were assigned road numbers 1800 through 1811 and were immediately put into passenger service. These new 4-8-4s began to handle trains with as many as 21 heavyweight cars, eliminating the need for double-heading and running extra sections of many of the Richmond, VA to Jacksonville, FL "Specials".

The ACL was very disappointed with their R-1s, and returned them to Baldwin for better counterbalancing of the 80 inch drive wheels. It seems the R-1s, as delivered, had a bad dynamic augment. It was so bad that it was even worse than the Norfolk & Western's J class 4-8-4s with their low 70 inch drive wheels. Even after Baldwin checked their math, and put new disk drivers on the ACL R-1s, they still had unacceptable amounts of dynamic augment at high speeds. As soon as the ACL could replace them with EMD E-3 and E-6 diesel electrics, the Standard Railroad of the South put its latest and largest steamers in freight service.