The returns
1866 Senate Elections

No President race in 1866.
Table of returns — 31 states
| California | Popular Democratic (Popular Democratic) | 32.1% |
|---|---|---|
| Chihuahua | Popular Democratic (Popular Democratic) | 8.3% |
| Connecticut | National (National) | 19.5% |
| Delaware | National (National) | 40.9% |
| Illinois | Popular Democratic (Popular Democratic) | 16.0% |
| Iowa | Popular Democratic (Popular Democratic) | 15.6% |
| Kentucky | National (National) | 41.8% |
| Kiowah | Popular Democratic (Popular Democratic) | 17.6% |
| Maine | Popular Democratic (Popular Democratic) | 16.8% |
| Marshall | National (National) | 10.8% |
| Maryland | National (National) | 43.8% |
| Massachusetts | Popular Democratic (Popular Democratic) | 12.5% |
| Miami | National (National) | 3.0% |
| Michigan | Popular Democratic (Popular Democratic) | 12.6% |
| Minnesota | Popular Democratic (Popular Democratic) | 20.1% |
| Missouri | National (National) | 38.2% |
| New Hampshire | Popular Democratic (Popular Democratic) | 0.7% |
| New Jersey | National (National) | 15.6% |
| New Mexico | Popular Democratic (Popular Democratic) | 5.7% |
| New York | Popular Democratic (Popular Democratic) | 36.8% |
| Ohio | Popular Democratic (Popular Democratic) | 13.1% |
| Oregon | National (National) | 2.7% |
| Pennsylvania | Popular Democratic (Popular Democratic) | 3.5% |
| Rhode Island | Popular Democratic (Popular Democratic) | 9.5% |
| Rio Grande | National (National) | 2.0% |
| Sonora | National (National) | 2.3% |
| Vermont | Popular Democratic (Popular Democratic) | 19.1% |
| Virginia | Popular Democratic (Popular Democratic) | 4.6% |
| Washoe | Popular Democratic (Popular Democratic) | 35.3% |
| Wisconsin | Popular Democratic (Popular Democratic) | 15.7% |
| Yucatan | Popular Democratic (Popular Democratic) | 73.5% |