Elections to theMassachusetts 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, theMassachusetts 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 theUnited States Constitution by a separate ratifying convention; the reaction divided the state (and nation) betweenFederalists andAnti-Federalists, though the factions did not appear as strictly formal political parties until 1789.

The elections were also held during the midst ofShays' 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:

• Barnstable County: 1
• Berkshire County: 2
• Bristol County: 3
• Cumberland County: 1
• Dukes and Nantucket Counties: 1
• Essex County: 6
• Hampshire County: 4
• Lincoln County: 1
• Middlesex County: 5
• Plymouth County: 3
• Suffolk County: 6
• Worcester County: 5
• York County: 2

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 fromWeston, 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.^[13]

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.

• Massachusetts Senate elections
• 1787 state legislature elections in the United States

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