Elections to the Massachusetts Senate were held during 1787 to elect 40 State Senators. Candidates were elected at the county level, with some counties electing multiple Senators.
For election, a candidate needed the support of a majority of those voting. If a seat remained vacant because no candidate received such majority, the Massachusetts General Court was empowered to fill it by a majority vote of its members.
The primary issue in this race was the ongoing ratification of the United States Constitution by a separate ratifying convention; the reaction divided the state (and nation) between Federalists and Anti-Federalists, though the factions did not appear as strictly formal political parties until 1789.
The elections were also held during the midst of Shays' Rebellion, an armed uprising in Western Massachusetts against the national government, formed in opposition to the ongoing debt crisis.
The apportionment of seats by population was as follows:
Both candidates were elected.
Because Mayhew failed to achieve a majority, the election was put to the General Court, which certified his election with near unanimity.
Dalton, Choate, and Greenleaf would subsequently be elected by the General Court.
Hastings, Smead, and Phelps were subsequently elected by the General Court.
Based on returns from Weston, Ezra Sergant, Abraham Fuller, James Prescot, Joseph Curtis, Thomas Fairweather, Joseph Roberts, John Brooks, and Abner Sanderson also received votes, but how many they received county-wide is unknown.
Hosmer and MacFarland were subsequently elected by the General Court.
Turner and Cushing were subsequently elected by the General Court.
Austin and Dunbar were subsequently elected by the General Court. (No result is listed for Dunbar's election.)
No candidate received a majority. Cutts and Jordan were subsequently elected by the General Court.