Short answers, pulled from the story.
Prudence Crandall admitted an African American girl to her all-white Canterbury Female Boarding School in 1832. This event triggered immediate and violent public backlash including a mob attack on the school.
The United States Supreme Court upheld the constitutionality of segregation in the case of Plessy v. Ferguson in 1896. This ruling established the separate but equal doctrine that remained law for nearly sixty years until Brown v. Board of Education in 1954.
President Harry S. Truman signed Executive Order 9981 on the 26th of July 1948 to end racial segregation in the United States Armed Forces. This order followed pressure from African Americans and progressives after World War II ended.
The Home Owners Loan Corporation created eligibility maps known as redlining that determined mortgage access based on racial composition. The National Housing Act of 1934 allowed the government to make low-interest loans available through the Federal Housing Administration while explicitly denying them to Black families.
Rosa Parks refused to be moved to the back of a bus for a white passenger on the 4th of December 1955 in Montgomery, Alabama. Her act of defiance sparked the Montgomery bus boycott which lasted from 1955 to 1956.