Final answer:
The one person, one vote principle mandates nearly exactly equal populations in Congressional districts within a state, ensuring each vote has the same weight and eliminating malapportionment.
Step-by-step explanation:
The one person, one vote principle requires almost exact mathematical equality between Congressional districts within a state. This principle ensures that each person's vote in a Congressional election is worth as much as anyone else's within the state, avoiding over or underrepresentation, which is termed as malapportionment. According to the U.S. Supreme Court's decision in Reynolds v. Simms (1964) and the subsequent use of the equal protection clause of the 14th Amendment, electoral districts must have roughly the same number of people in each equivalent district. Therefore, states must periodically engage in the processes of reapportionment and redistricting, which are largely based on population changes recorded by the official U.S. Census conducted every ten years.