As it might be expected following a war between two parts of one nation that would cost 600,000 or 700,00 lives, depending on who you ask, literature in the United States after the Confederate surrender was not a particularly cheerful experience. The Romantics of the 1840's and 1850's--Thoreau, Emerson, Hawthorne--were yesterday's news, as were their lofty ideas about nature, about God, about the possibilities of the human spirit. Some people even insisted that Romanticism had fostered ideals of glory and heroism that had hastened the nation's march toward a war that could have been avoided. Instead, Americans moved toward a style that seems more commensurate with the tragedy that began in 1861 at Fort Sumter, South Carolina, and ended, in a manner of speaking, with the assassination of President Lincoln shortly after the surrender at Appomattox Courthouse, prompting Walt Whitman to write of the President, "O Captain! my Captain! our fearful trip is done; The ship has weathered every rack, the prize we sought is won."
Experts in the field typically date the onset of Realism as being anywhere between the years right after the Civil War to the last two or three decades of the 19th century. Realists like Henry James and Stephen Crane created narratives exploring the impact of a rapidly changing, and not altogether desirable world on the individual, while writers and artists like Jacob Riis documented city residents living in some of the most unpleasant conditions imaginable. It is also noteworthy that utopian communities began to make an appearance around this time.