Lincoln's removal from New Salem to Springfield and his entrance into a law partnership with Major John T. Stuart begin a distinctively new period in his career.

Nicolay and Hay also edited Lincoln's Works in twelve volumes (1905). For some time after his return to the United States he edited the Chicago Republican. In the 1992 documentary Lincoln the German-born Nicolay is voiced by the Austrian-born actor Arnold Schwarzenegger.

He was Marshal of the United States Supreme Court (1872–87). The resulting biography is a definitive resource on Lincoln and his times. John George Nicolay (born February 26 1832 as Johann Georg in Essingen Rhenish Bavaria – September 26 1901) was an American (German-born) biographer secretary of US President Abraham Lincoln and member of the German branch of the Nicolay family.