<Tr> <Td> 15! August 2, 1923--March 4, 1925 </Td> <Td> 580 </Td> <Td> Calvin Coolidge succeeded to presidency . </Td> <Td> Charles G. Dawes, following election of 1924 . </Td> </Tr> <Tr> <Td> 16! April 12, 1945--January 20, 1949 </Td> <Td> 1,379 </Td> <Td> Harry S. Truman succeeded to presidency . </Td> <Td> Alben W. Barkley, following election of 1948 . </Td> </Tr> <Tr> <Td> 17! November 22, 1963--January 20, 1965 </Td> <Td> 425 </Td> <Td> Lyndon B. Johnson succeeded to presidency . </Td> <Td> Hubert Humphrey, following election of 1964 . </Td> </Tr> <Tr> <Td> 18! October 10, 1973--December 6, 1973 </Td> <Td> 57 </Td> <Td> Spiro Agnew resigned . </Td> <Td> Gerald Ford, following confirmation by Congress . </Td> </Tr>

Who selects the replacement for a vice president who died in office