On July 2, 1964, President Lyndon B. Johnson signed the Civil Rights Act into law, marking a major federal intervention against racial segregation and discrimination. The law outlawed segregation in public accommodations, prohibited employment discrimination, and strengthened voting rights enforcement. Its passage and the federal effort to implement its provisions prompted an immediate and sometimes violent backlash in parts of the South where segregation was deeply entrenched. Federal enforcement took several forms: the Justice Department filed suits to desegregate schools and businesses; federal marshals and other agents protected activists and Black citizens asserting their newly recognized rights; and the Office of Equal Employment Opportunity investigated discriminatory hiring. Local responses varied. In many communities, white political leaders, business owners, and private citizens resisted compliance through legal maneuvers, economic pressure, and extra-legal intimidation. Violence and intimidation were common tools of resistance. Civil rights organizations reported incidents of beatings, bombings, arson, and mob attacks aimed at Black residents, NAACP and Southern Christian Leadership Conference (SCLC) activists, and those who cooperated with federal authorities. In some cases, federal agents were themselves assaulted while escorting activists to desegregated facilities or while protecting demonstrators. Ku Klux Klan–linked violence remained a persistent threat in numerous counties, and local law enforcement sometimes colluded with or turned a blind eye to attacks. High-profile episodes of violence helped shape national perceptions. In addition to continuing assaults on Freedom Riders earlier in the decade and the murders of activists in prior years, the period after the Act’s passage saw renewed tensions as plaintiffs and federal officials pressed for compliance. Some white communities organized mass protests, boycotts, or “school choice” measures to avoid integration. In rural areas with limited oversight, sanctions imposed by federal courts could provoke direct confrontations when federal marshals attempted to enforce rulings. The federal government’s response combined litigation, administrative action, and—when necessary—deployment of federal personnel to protect civil rights. The Department of Justice pursued desegregation suits, while the newly empowered Equal Employment Opportunity Commission (EEOC), created by the Act, began to investigate employment discrimination complaints. Where local authorities failed to protect citizens or comply with court orders, federal courts could issue injunctions and authorize federal enforcement measures. These interventions sometimes defused immediate crises but could also intensify local hostility toward federal officials and the communities they were seen to represent. The backlash had human and political consequences. For Black Americans and civil rights activists, violent resistance reinforced the dangers of asserting new legal rights but also underscored the importance of federal protections. For political leaders, the clashes highlighted deep regional divisions over race, law, and federal authority. Over time, sustained federal enforcement, coupled with ongoing activism, made meaningful though uneven progress in dismantling legal segregation and expanding access to voting and employment. Nonetheless, the period immediately following the Act’s passage demonstrated that legal change did not automatically translate into social acceptance, and that enforcement often required persistent federal commitment in the face of violent opposition. Historical accounts of this period rely on contemporary newspaper reporting, Justice Department records, civil rights organizations’ documentation, and later scholarly studies. Specific incidents of violence and the intensity of backlash varied by locality and are documented in regional archives and oral histories. While the Civil Rights Act established powerful tools for change, its implementation exposed deep-seated resistance that federal authorities, civil rights groups, and Black communities confronted throughout the 1960s.