What minorities made the biggest gain in the 1970's?
In the 1980 annual report of the National Urban League, it was pointed out that many of the promises of the Civl Rights Movement had not materialized. Still, for black Americans there were some gains, and the numbers of blacks in the workforce increased although the percentage of all categories (color, ethnic and gender) decreased slightly due to the recession following the Viet Nam War. There were also improvements in the lot of migrant farm laborers of all colors, and Hispanic and black citizens were recipients of some help from the Affirmative Action Program. On the other hand, by 1980 almost one third of African-Americans between the ages of 16 and 24 were unemployed.
The "minority" which benefited the most from the 1970s was women, not actually a minority except in the workforce. Even though the Equal Rights Amendment in the end did not pass the states' legislatures, women in the workforce went up and women's rights became a topic of debate which gradually included civil rights, legal rights and workers' rights. At the end of the decade women were still being paid only two-thirds the salary of men doing the same jobs.
The most central piece of legislation for minorities was the Civil Rights Act of 1964, but it has taken many years for American society at large to change. Except for the gradual effect of change slowly but surely coming, there were not really any actual dramatic gains made by minorities in the '70s.