Question: How many states only replaced or added one seat during the 36th United States Congress ?

text: 36th United States Congress
Changes in membership -- Senate
See also : List of special elections to the United States Senate Replacements : 4 Democrats ( D ) : no net change Republicans ( R ) : no net change Deaths : 1 Resignations : 1 Interim appointments : 1 Withdrawals : 13 Total seats with changes : 16
The Thirty-sixth United States Congress was a meeting of the legislative branch of the United States federal government, consisting of the United States Senate and the United States House of Representatives. It met in Washington, D.C. from March 4, 1859, to March 4, 1861, during the third and fourth years of James Buchanan's presidency. The apportionment of seats in the House of Representatives was based on the Seventh Census of the United States in 1850. The Senate had a Democratic majority, and the House had a Republican plurality.
State ( class ) Vacator Reason for change Successor Date of successor 's formal installation
Oregon ( 2 ) Vacant Successor elected late due to legislature 's failure to elect Edward D. Baker ( R ) October 2 , 1860
California ( 1 ) David C. Broderick ( D ) Died September 16 , 1859 Interim successor was appointed to continue the term Henry P. Haun ( D ) November 3 , 1859
Texas ( 1 ) Matthias Ward ( D ) Interim appointee lost nomination to finish the term Successor elected December 5 , 1859 Louis Wigfall ( D ) December 5 , 1859
California ( 1 ) Henry P. Haun ( D ) Interim appointee lost election to finish the term Successor elected March 5 , 1860 Milton Latham ( D ) March 5 , 1860
South Carolina ( 2 ) James Chesnut , Jr. ( D ) Withdrew November 10 , 1860 Vacant Not filled this Congress
South Carolina ( 3 ) James H. Hammond ( D ) Withdrew November 11 , 1860 Vacant Not filled this Congress
Mississippi ( 2 ) Albert G. Brown ( D ) Withdrew January 12 , 1861 Vacant Not filled this Congress
Maine ( 1 ) Hannibal Hamlin ( R ) Resigned January 17 , 1861 , to become Vice President of the United States . Successor elected January 17 , 1861 Lot M. Morrill ( R ) January 17 , 1861
Alabama ( 3 ) Benjamin Fitzpatrick ( D ) Withdrew January 21 , 1861 Vacant Not filled this Congress
Alabama ( 2 ) Clement C. Clay ( D ) Withdrew January 21 , 1861 Vacant Not filled this Congress
Florida ( 1 ) Stephen Mallory ( D ) Withdrew January 21 , 1861 Vacant Not filled this Congress
Florida ( 3 ) David L. Yulee ( D ) Withdrew January 21 , 1861 Vacant Not filled this Congress
Mississippi ( 1 ) Jefferson Davis ( D ) Withdrew January 21 , 1861 Vacant Not filled this Congress
Georgia ( 3 ) Alfred Iverson , Sr. ( D ) Withdrew January 28 , 1861 Vacant Not filled this Congress
Kansas ( 2 ) New seat New state admitted to the Union January 29 , 1861 Senator was not elected until the next Congress Vacant Not filled this Congress
Kansas ( 3 ) New seat New state admitted to the Union January 29 , 1861 Senator was not elected until the next Congress Vacant Not filled this Congress
Georgia ( 2 ) Robert Toombs ( D ) Withdrew February 4 , 1861 Vacant Not filled this Congress
Louisiana ( 2 ) Judah P. Benjamin ( D ) Withdrew February 4 , 1861 Vacant Not filled this Congress
Louisiana ( 3 ) John Slidell ( D ) Withdrew February 4 , 1861 Vacant Not filled this Congress
Tennessee ( 2 ) Alfred O. P. Nicholson ( D ) Withdrew March 3 , 1861 Vacant Not filled this Congress