<P> From east to west, the times zones of the contiguous United States are: </P> <Ul> <Li> The Eastern standard time zone: (Zone R), which comprises roughly the states on the Atlantic coast and the eastern two thirds of the Ohio Valley . </Li> <Li> The Central standard time zone: (Zone S), which comprises roughly the Gulf Coast, Mississippi Valley, and Great Plains . </Li> <Li> The Mountain standard time zone: (Zone T), which comprises roughly the states that include the Rocky Mountains . </Li> <Li> The Pacific standard time zone: (Zone U), which comprises roughly the states on the Pacific coast, plus Nevada and the Idaho panhandle . </Li> </Ul> <Li> The Eastern standard time zone: (Zone R), which comprises roughly the states on the Atlantic coast and the eastern two thirds of the Ohio Valley . </Li> <Li> The Central standard time zone: (Zone S), which comprises roughly the Gulf Coast, Mississippi Valley, and Great Plains . </Li>

Where does the time zone change to eastern