This is a complete list of members of the United States Senate during the 37th United States Congress listed by seniority, from March 4, 1861, to March 3, 1863.
Order of service is based on the commencement of the senator's first term. Behind this is former service as a senator (only giving the senator seniority within his or her new incoming class), service as vice president, a House member, a cabinet secretary, or a governor of a state. The final factor is the population of the senator's state. [1] [2] [3] [4]
Senators who were sworn in during the middle of the Congress (up until the last senator who was not sworn in early after winning the November 1862 election) are listed at the end of the list with no number.
| Class | Terms of service of senators that expired in years |
|---|---|
| Class 1 | Terms of service of senators that expired in 1863 (CA, CT, DE, FL, IN, MA, MD, ME, MI, MN, MO, MS, NJ, NY, OH, PA, RI, TN, TX, VA, VT, and WI.) [5] |
| Class 2 | Terms of service of senators that expired in 1865 (AL, AR, DE, GA, IA, IL, KS, KY, LA, MA, ME, MI, MN, MS, NC, NH, NJ, OR, RI, SC, TN, and TX.) [6] |
| Class 3 | Terms of service of senators that expired in 1867 (AL, AR, CA, CT, FL, GA, IA, IL, IN, KS, KY, LA, MD, MO, NC, NH, NY, OH, OR, PA, SC, VT, and WI.) [7] |