<Table> <Tr> <Th_colspan="2"> United States Numbered Highway System </Th> </Tr> <Tr> <Td_colspan="2"> Design changes of U.S. Highway shield </Td> </Tr> <Tr> <Td_colspan="2"> Map of the present U.S. Highway network </Td> </Tr> <Tr> <Th_colspan="2"> System information </Th> </Tr> <Tr> <Td_colspan="2"> Maintained by state or local governments; numbers and routings assigned by AASHTO </Td> </Tr> <Tr> <Th> Length: </Th> <Td> 157,724 mi (253,832 km) </Td> </Tr> <Tr> <Th> Formed: </Th> <Td> November 11, 1926 </Td> </Tr> <Tr> <Th_colspan="2"> Highway names </Th> </Tr> <Tr> <Th> US Highways: </Th> <Td> U.S. Highway nn (US nn) U.S. Route nn (US nn) </Td> </Tr> <Tr> <Th_colspan="2"> System links </Th> </Tr> <Tr> <Td_colspan="2"> <Ul> <Li> United States Numbered Highway System </Li> </Ul> <Ul> <Li> List </Li> <Li> Special </Li> <Li> Divided </Li> <Li> Replaced </Li> </Ul> </Td> </Tr> </Table> <Tr> <Th_colspan="2"> United States Numbered Highway System </Th> </Tr> <Tr> <Td_colspan="2"> Design changes of U.S. Highway shield </Td> </Tr> <Tr> <Td_colspan="2"> Map of the present U.S. Highway network </Td> </Tr>

How many roads does florida have that are designated as part of the national highway system