Isaac L. Ellwood, rancher and barbed wire manufacturer, was born in Springfield Hollow, New York, on August 12, 1833. As a boy he exhibited the initiative and enterprise that made him one of America's great businessmen by selling sauerkraut to barge hands on the Erie Canal. In 1851 he followed the gold rush to California, from where he returned in 1855 with a capital of nearly $3,000, with which he opened a hardware and implement store in DeKalb, Illinois. There he married Harriet Augusta Miller on January 27, 1859. The couple had six children. Ellwood acquired several farm properties around DeKalb and after the Civil War began importing and breeding Percheron draft horses.
His interest in farming directed his attention to the need for a fencing material that would contain livestock. He patented a type of barbed wire but concluded that the wire patented by Joseph F. Glidden was more practical. With Glidden, Ellwood formed the I. L. Ellwood Manufacturing Company in 1873 and began producing a two-strand, twisted barbed wire in a back room of his hardware store. Success was almost immediate, for the Glidden-Ellwood wire fulfilled a practical need, especially for ranchers on the western plains. In 1881 the company expanded and reorganized as the Superior Barbed Wire Company, and in 1898 it merged into the American Steel and Wire Company, a predecessor of United States Steel.
In the meantime Ellwood became interested in ranching. He made a trip to Texas in 1889 and purchased the Renderbrook Ranch of some 130,000 acres in Mitchell County from John W. and Dudley H. Snyder, for which Ellwood adopted the Spade brand. In 1891 he acquired an additional 128,000 acres northwest of Lubbock from the Snyder brothers. He added 45,000 acres in 1902 and additional acreage in 1906 to bring the total size of his ranch, which was known as the Spade Ranch, to 265,000 acres, thereby increasing his total Texas holdings to 395,000 acres. After the merger with American Steel and Wire, Ellwood focused on his Texas ranches, although his home remained in DeKalb, where he had other investments. He died in DeKalb, Illinois, on September 11, 1910.