Answer:
The Civil Rights action that resulted in the participation of thousands of non-African Americans was the March on Washington.
Explanation:
The March on Washington for Jobs and Freedom was a major political demonstration in Washington, DC, on August 28, 1963, organized and led, among others, by the lawyer, pastor, human rights activist and peace activist Martin Luther King, who brought together more than 250,000 people in the city to clamor, address, pray and sing for freedom, work, social justice and an end to racial segregation against the country's black population.
During the day, protesters from every part of the country, mainly African Americans but with a notorious white participation (about 20% of total demonstrators), arrived to Washington. The protests took place in deep order and civility, and its worldwide repercussion made it the greatest political force for the passage of Civil Rights Act and the Voting Rights Act in 1964 and 1965.