The table does not include appointments or special elections, though it does include elections that occurred upon a state delegation's admission or readmission to the Senate.
The table also includes elections that filled vacancies to unexpired terms that had never been filled due to legislative deadlock or an elected candidate's failure to qualify.
The table does not denote post-election party switching.
A * sign indicates that a state elected that party at least 80 percent of the time.
No * sign indicates that the state elected that party between 60 and 80 percent of the time.