Both the North and the South were changed by the Civil War. In the North, the change was more subtle, save for the physical destruction that resulted from battles at locations like Gettysburg. By and large, however, the war was fought in the South, and the changes it brought overwhelmingly affected the former Confederacy far more than the victorious North.
First, as mentioned, most of the war was fought in the South, leaving considerable damage to both property and lives. The plantation structure of the much of the South had to endure the passage of armies through fields, and southern cities were scarred by the destruction imposed by Union armies.
Second, and of far greater significance, the South could no longer employ slave labor, an obvious source of cheap manpower. With the abolishment of slavery, the entire southern economy was radically altered.
Third, the policy of Reconstruction, imposed from the North, was extraordinarily intrusive from the vantage of the South, and threatened the only way of life southerners had ever known. "Carpetbaggers" from the North settled in the South and brought northern perspectives with them. Resentment from the South, stemming both from the abolishment of slavery and from Reconstruction, bred the anger and violence exemplified by the birth of the Ku Klux Klan, which spread rapidly througout the South.