The Legislature shall divide the state into six contiguous and compact districts of approximately equal population, which shall be numbered from one to six, which shall be known as the Supreme Court judicial districts. The Legislature shall redistrict the state after each federal decennial census. In any such redistricting, county lines shall be followed whenever practicable, but other established lines may be followed at the discretion of the Legislature. Such districts shall not be changed except upon the concurrence of a majority of the members of the Legislature. Whenever the Supreme Court is redistricted, the judges serving prior to the redistricting shall continue in office, and the law providing for such redistricting shall where necessary specify the newly established districts which they shall represent for the balance of their terms.