(RNS) — The U.S. Supreme Court issued a decision on Wednesday (April 29) that struck down a key provision of the Voting Rights Act, making it nearly impossible to challenge racially discriminatory voting maps without proving intentional discrimination. Hours after the ruling, Florida’s Legislature approved a new congressional map, skewed in Republicans’ favor, and many experts are predicting a historic drop in Black representation in Congress — and much longer lines for Black voters .    None of this is surprising. The history of civil rights in America is one in which there is progress followed by retrenchment, expansion followed by restriction.    In 1870, the 15th Amendment promised that the right to vote could not be denied on account of race. Within a generation, that promise was hollowed out by poll taxes, literacy tests and racial terror.…