In which court case was the County Unit System declared invalid?

The County Unit System was declared invalid in the case of Gray v. Sanders. This Supreme Court decision addressed the issue of electoral representation in Georgia, specifically focusing on the unequal weighting of votes in primary elections due to the County Unit System. This system gave more power to rural counties compared to urban ones, leading to a violation of the "one person, one vote" principle established by the Fourteenth Amendment.

In Gray v. Sanders, the Court concluded that the County Unit System diluted the voting power of citizens in urban areas, making elections unfair and unconstitutional. This landmark ruling significantly impacted the structure of electoral systems, ensuring that each vote carries equal weight and reinforces the democratic principle of equal representation.

Understanding this case is essential for grasping how the judiciary can influence electoral policies and protect voting rights, which is a crucial aspect of U.S. and Georgia history. The other cases listed, while significant in their own rights, dealt with different issues such as civil rights and racial segregation, and did not address the specific voting system in question.