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The 193rd General Court of the Commonwealth of Massachusetts

Computing Congressional Apportionment

Computing Congressional Apportionment

Since that first census in 1790, five methods of apportionment have been used. The current method used, the Method of Equal Proportions, was adopted by congress in 1941 following the census of 1940. This method assigns seats in the House of Representatives according to a "priority" value. The priority value is determined by multiplying the population of a state by a "multiplier."

For example, each of the 50 states is assigned one seat out of the current total of 435. The next, or 51st seat, goes to the state with the highest priority value and thus became that state's second seat. This continues until all 435 seats are assigned to the states.

Equal Proportions Method – P x Multiplier = Priority Value

P - represents a state's total population

n - represents the number of seats a state would have if it gained a seat (because all states automatically received one seat the next seat gained is "seat two," and the next "seat three," and the next "seat four," and so on.).

The multiplier equals:

The higher the Priority Value, the more seats per state.
Additional Congressional Seats Awarded to Massachusetts based on the Apportionment Population of 7,033,469 released by the Census on April 26, 2021

Additional SeatHouse Seat #Priority Value
2814,973,413.6251654
31262,871,401.6952806
41722,030,387.6102434
52171,572,731.4801638
62631,284,129.8762711
73091,085,287.8285545
8355939,886.8299463
9399828,902.2708609

To learn more on how Congressional Seats are awarded please visit:  U.S. Census Bureau: Computing Apportionment

History of Massachusetts Membership in the United States House of Representatives

Members of Congress from Massachusetts
Census Year Members
Initial Apportionment117898
1st Census179014
2nd Census180017
3rd Census2181020
4th Census182013
5th Census183012
6th Census184010
7th Census185011
8th Census186010
9th Census187011
10th Census188012
11th Census189013
12th Census190014
13th Census191016
14th Census3192016
15th Census193015
16th Census4194014
17th Census195014
18th Census196012
19th Census197012
20th Census198011
21st Census199010
22nd Census200010
23rd Census20109
24th Census20209

1. Constitutional Apportionment (Article 1, Section 2).

2. Formerly part of Massachusetts, when Maine achieved statehood in 1820, Congress assigned the new state one At-Large Representative, leaving Massachusetts with its allotted 20 Representatives. In the 17th Congress (1821–1823), the final Congress before the apportionment following the 4th Census (1820), Congress reassigned seven Massachusetts Representatives to Maine, leaving Massachusetts with 13 Members of the House.

3. No change was made after the 14th Census (1920), as Congress could not agree on a method for apportionment.

4. The current method of apportionment began following the 1940 Census

Visit for More Information: Office of the Clerk, House History: Congressional Apportionment

For more information on Congressional Apportionment please visit:

Office of the Clerk, House History: Congressional Apportionment

U.S. Census Bureau, Congressional Apportionment