On March 10, 1891, U.S. Patent No. 447,918 issued to Almon B. Strowger on an Automatic Telephone Exchange:

Almon help form the Strowger Automatic Telephone Exchange Company, and installed and opened the first commercial exchange in his hometown of La Porte, Indiana. Strowger sold his patents to his associates in 1896 for $1,800 and sold his share in the Automatic Electric Company for $10,000 in 1898. He died a wealthy man on May 26, 1902, in St. Petersburg, Florida. His patents were subsequently resold to Bell Systems for $2.5 million in 1916.