<Tr> <Th_colspan="2"> Eminem singles chronology </Th> </Tr> <Tr> <Td_colspan="2"> <Table> <Tr> <Td> "Walk on Water" (2017) </Td> <Td> "River" (2017) </Td> <Td> "Nowhere Fast" (2018) </Td> </Tr> </Table> </Td> </Tr> <Table> <Tr> <Td> "Walk on Water" (2017) </Td> <Td> "River" (2017) </Td> <Td> "Nowhere Fast" (2018) </Td> </Tr> </Table> <Tr> <Td> "Walk on Water" (2017) </Td> <Td> "River" (2017) </Td> <Td> "Nowhere Fast" (2018) </Td> </Tr>

What is the song river about by eminem