Short answers, pulled from the story.
Plessy v. Ferguson (1896) and Brown v. Board of Education (1954) serve as bookends of this era. Plessy established "separate but equal" racial segregation as constitutional doctrine, while Brown overturned it, ruling that segregated public schools denied minority children equal educational opportunities.
In 1896, the U.S. Supreme Court in Plessy v. Ferguson upheld state-mandated racial segregation in public transportation under the "separate but equal" doctrine. The ruling provided the legal foundation for Jim Crow laws throughout the South, mandating separate public facilities including schools, restrooms, and transportation. Justice Harlan was the only dissenting vote.
The NAACP was founded in 1909 by W. E. B. Du Bois and others including Mary White Ovington, Oswald Garrison Villard, Julius Rosenwald, and Rabbi Emil G. Hirsch. Its early legal strategy focused on challenging Jim Crow laws in court, winning rulings against residential segregation in Buchanan v. Warley and against grandfather clauses in Guinn v. United States (1915).
Thurgood Marshall headed the NAACP's legal department alongside Charles Hamilton Houston and led a decades-long litigation campaign to reverse the "separate but equal" doctrine. He argued the case Briggs v. Elliott as the first direct challenge to segregation in education, and consolidated several cases including Brown v. Board of Education, which the Supreme Court ruled on unanimously in May 1954.
The Brotherhood of Sleeping Car Porters was a union founded in 1925 and led by A. Philip Randolph. After a ten-year campaign, it won recognition from the Pullman Company in 1935 and a contract in 1937, becoming the only Black-led union within the American Federation of Labor in 1935. Its members, including Edgar Nixon, went on to play significant roles in civil rights struggles in later decades.
While the NAACP pursued integration through the courts, Garvey's UNIA promoted Pan Africanism, economic independence within segregation, and encouraged African Americans to "return to Africa" in spirit. Garvey claimed eleven million members for the UNIA in the early 1920s. The federal government convicted Garvey for mail fraud in 1922, and he was deported to Jamaica in 1927.