and Linn counties in the Council of the Third Legislative Assembly as a Democrat. He was re-elected to the following year to the Fourth Legislative Assembly. In 1845, he moved to Dubuque, Iowa, and became the editor of the Miners' Express. In Dubuque he began practicing law again, this time in partnership with J. J. Dyer. Greene's law practice was so successful that he was appointed to be a justice of the Iowa Supreme Court in 1847, to fill the vacancy left by Justice Thomas Stokeley Wilson. He served from November 1, 1847 to January 9, 1855. He was also the reporter of the Supreme Court, so he compiled the decisions of the court in the four-volume G. Greene Reports. In 1849, he became one of the founders of Cedar Rapids, Iowa by surveying and laying out the site of the town. He began living in Cedar Rapids in 1851. He also contributed to the financial development of the city. During the Panic of 1857 he was connected with the management of nine banks in the city. In 1859, Greene formed a law partnership with Cyrus Bently in Chicago, Illinois. He practiced law and lived there for five years. In the winter of 1864 he moved to McGregor, Iowa and helped his brothers build the McGregor Western Railroad. During this time, and several years later, he helped build the Rockford, Rock Island & St. Louis Railroad. He returned to Cedar Rapids after this, and began practicing law with Judge Dudley and his son-in-law A. S. Belt. The firm represented the Chicago & Northwestern Railroad. Greene continued to be involved with railroads, and became president of the Burlington, Cedar Rapids & Minnesota Railroad, which he took an active part in building. When the railroad went bankrupt it was purchased and operated under the name Burlington, Cedar Rapids & Northern Railroad. He constructed several smaller railroads in Iowa, Illinois, Minnesota, Missouri, and Kansas. In addition to being a successful lawyer and business man, Greene founded the Grace Episcopal Church, donated the grounds for the church and rectory, and also served as the warden of it. He served as president of the board of trustees of Coe Collegiate Institute, which was later renamed Coe College. In 1872, he changed his party affiliation from Democrat to Republican. Greene was also a mason and was first Past Master of Crescent Lodge #25, Cedar Rapids (1851–52).