Long before he became president of Seaboard, Warfield played a large role in its early 1900s expansion phase as one of its directors and investors. Warfield and his partners expanded the line from its base Virginia-North Carolina route into Florida, Alabama, Georgia, and later up to Washington D.C. and New York. As president, Warfield continued this trend, expanding the road further west and south, and by the end of his tenure as president, Seaboard controlled some 4,500 miles of track.