On April 14, 1900, the Seaboard Air Line Railway was incorporated, comprising 19 railroads in which it owned all or most of the capital stock.
Williams was the first president of the new corporation, which advertised its north–south route as the "Florida-West India Short Line."
James H. Dooley, veteran of several rail mergers in the South, helped organize the SAL and served as chairman of SAL's executive council.

On June 3, 1900, through service from New York to Tampa, Florida, was inaugurated, with trains operated by the Pennsylvania Railroad from New York to Washington, D.C.; by the Richmond, Fredericksburg and Potomac Railroad from Washington to Richmond; and by the Seaboard from Richmond to Tampa, an arrangement that lasted until the creation of Amtrak in 1971.
On July 1, 1900, the Seaboard formally assumed operation of the Georgia and Alabama, the FC&P and the Atlantic, Suwannee River and Gulf railroads.
In 1903, the FC&P, which had been controlled through stock ownership and operated separately under a lease agreement, was formally consolidated within the Seaboard.

In 1904, Seaboard subsidiary Atlanta and Birmingham Air Line Railway, purchased the previous year, completed construction and extended the Atlanta route to Birmingham, Alabama, the largest center of iron and steel production in the South, and a valuable endpoint for the Seaboard.

Unfortunately, the new 2,600-mile railroad did not prosper as expected in its early years.
Thomas Fortune Ryan, who had opposed the Williams syndicate when it purchased the controlling interests in the various Seaboard companies, succeeded in assuming control of the railroad in 1904.
Ryan's policies, however, proved disastrous for the Seaboard's finances.
Following the Panic of 1907, the railroad went into receivership and Ryan was ousted.
S. Davies Warfield, a Seaboard director and member of the railroad's executive committee, who had assisted Williams in forming the corporation, was appointed one of the receivers, and was subsequently named chairman.
In 1912, Warfield — who was the uncle of the Baltimore-born Wallis Warfield Simpson, the future Duchess of Windsor – became the majority stock owner of the Seaboard.
By 1915, the railroad had recovered.
However, along with most other U.S. railroads, the Seaboard was nationalized during the railroad crisis brought on by World War I and was run by the United States Railroad Administration from December 28, 1917, to March 1, 1920.
On April 14, 1900, the Seaboard Air Line Railway was incorporated, comprising 19 railroads in which it owned all or most of the capital stock. Williams was the first president of the new corporation, which advertised its north–south route as the "Florida-West India Short Line." James H. Dooley, veteran of several rail mergers in the South, helped organize the SAL and served as chairman of SAL's executive council.
On June 3, 1900, through service from New York to Tampa, Florida, was inaugurated, with trains operated by the Pennsylvania Railroad from New York to Washington, D.C.; by the Richmond, Fredericksburg and Potomac Railroad from Washington to Richmond; and by the Seaboard from Richmond to Tampa, an arrangement that lasted until the creation of Amtrak in 1971. On July 1, 1900, the Seaboard formally assumed operation of the Georgia and Alabama, the FC&P and the Atlantic, Suwannee River and Gulf railroads. In 1903, the FC&P, which had been controlled through stock ownership and operated separately under a lease agreement, was formally consolidated within the Seaboard.
In 1904, Seaboard subsidiary Atlanta and Birmingham Air Line Railway, purchased the previous year, completed construction and extended the Atlanta route to Birmingham, Alabama, the largest center of iron and steel production in the South, and a valuable endpoint for the Seaboard.
Unfortunately, the new 2,600-mile railroad did not prosper as expected in its early years. Thomas Fortune Ryan, who had opposed the Williams syndicate when it purchased the controlling interests in the various Seaboard companies, succeeded in assuming control of the railroad in 1904. Ryan's policies, however, proved disastrous for the Seaboard's finances. Following the Panic of 1907, the railroad went into receivership and Ryan was ousted. S. Davies Warfield, a Seaboard director and member of the railroad's executive committee, who had assisted Williams in forming the corporation, was appointed one of the receivers, and was subsequently named chairman. In 1912, Warfield — who was the uncle of the Baltimore-born Wallis Warfield Simpson, the future Duchess of Windsor – became the majority stock owner of the Seaboard. By 1915, the railroad had recovered. However, along with most other U.S. railroads, the Seaboard was nationalized during the railroad crisis brought on by World War I and was run by the United States Railroad Administration from December 28, 1917, to March 1, 1920.
Seaboard Air Line Railroad