<Tr> <Td> Washington, D.C. </Td> <Td> 7: 23 </Td> <Td> 16: 49 </Td> <Td> 9 h 26 min </Td> </Tr> <Tr> <Td> Los Angeles </Td> <Td> 6: 55 </Td> <Td> 16: 48 </Td> <Td> 9 h 53 min </Td> </Tr> <Tr> <Td> Dallas </Td> <Td> 7: 25 </Td> <Td> 17: 25 </Td> <Td> 9 h 59 min </Td> </Tr> <Tr> <Td> Miami </Td> <Td> 7: 03 </Td> <Td> 17: 35 </Td> <Td> 10 h 31 min </Td> </Tr>

When does the longest night of the year occur