<Table> <Tr> <Th_colspan="3"> (hide) <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> Cities during the American Civil War </Th> </Tr> <Tr> <Th> Union </Th> <Td> <Ul> <Li> Cincinnati </Li> <Li> Cleveland </Li> <Li> Harrisburg </Li> <Li> Indianapolis </Li> <Li> New York City </Li> <Li> Philadelphia </Li> <Li> Pittsburgh </Li> <Li> Washington, D.C. </Li> </Ul> </Td> <Td> </Td> </Tr> <Tr> <Th> Border states </Th> <Td> <Ul> <Li> Baltimore </Li> <Li> Lexington </Li> <Li> Louisville </Li> <Li> Romney, West Virginia </Li> <Li> St. Louis </Li> </Ul> </Td> </Tr> <Tr> <Th> Confederacy </Th> <Td> <Ul> <Li> Atlanta </Li> <Li> Charleston </Li> <Li> Columbia </Li> <Li> Mobile </Li> <Li> Nashville </Li> <Li> New Orleans </Li> <Li> Petersburg </Li> <Li> Richmond </Li> <Li> St. Augustine </Li> <Li> Selma </Li> <Li> Vicksburg </Li> <Li> Winchester </Li> <Li> Wilmington </Li> </Ul> </Td> </Tr> </Table> <Tr> <Th_colspan="3"> (hide) <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> Cities during the American Civil War </Th> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <Tr> <Th> Union </Th> <Td> <Ul> <Li> Cincinnati </Li> <Li> Cleveland </Li> <Li> Harrisburg </Li> <Li> Indianapolis </Li> <Li> New York City </Li> <Li> Philadelphia </Li> <Li> Pittsburgh </Li> <Li> Washington, D.C. </Li> </Ul> </Td> <Td> </Td> </Tr>

One significant innovation of urban america in the late 19th century was