Finally, in 1929 the Permanent Apportionment Act became law. It permanently set the maximum number of representatives at 435. In addition, the law determined a procedure for automatically reapportioning House seats after each census.

In 2026, "seat counts" depend entirely on the aircraft type and airline configuration. A standard narrow-body aircraft like the Boeing 737 or Airbus A320 typically holds between 150 and 190 seats in a two-class layout. Larger wide-body jets used for international travel, such as the Boeing 787 Dreamliner, generally feature 220 to 310 seats, while the massive Boeing 777 can accommodate 300 to 450 passengers depending on the specific model (e.g., the 777-300ER). Ultra-large jets like the Airbus A380 can hold over 500 people, though these are increasingly rare. For travelers, checking the specific "seat map" via apps like SeatGuru or the airline’s own website is vital, as a single airline may have multiple configurations for the same plane model to prioritize either business class luxury or economy capacity.