The Assembly districts were made up of entire towns, or city wards, forming a contiguous area, all within the same county.

The approximate party strength at this election, as expressed by the vote for Secretary of State, was: Republicans 301,000 and Democrats 273,000.

The Legislature met for the regular session at the Old State Capitol in Albany on January 2, 1866; and adjourned on April 20.

On February 16, the Legislature elected Benjamin F. Manierre (R) to succeed William McMurray (D) on March 1 as a Metropolitan Police Commissioner.

This session was called to hold the trial of George W. Smith, Judge of the Oneida County Court.