Final Answer:
The ban against black people joining the National Association of the Deaf (NAD) lasted for approximately 77 years, spanning from 1880 to 1957.
Step-by-step explanation:
The National Association of the Deaf (NAD) implemented a discriminatory policy in 1880 that excluded black individuals from joining the organization. This ban persisted for a substantial period, spanning nearly eight decades until 1957, when the NAD finally abolished this discriminatory practice.
The ban's duration can be calculated by subtracting the initial year of the ban (1880) from the year it was lifted (1957), resulting in a total of 77 years during which black individuals were prevented from joining the NAD. This extended period of exclusion from a prominent organization underscored the systemic racism prevalent within certain institutions during that era, highlighting the struggles faced by marginalized communities striving for inclusion and equality.
The lengthy duration of the ban against black individuals from joining the NAD underscores a dark chapter in the organization's history, showcasing the persistence of discriminatory practices in societal institutions. The eventual abolition of this ban in 1957 marked a crucial step toward inclusivity and equality within the NAD, reflecting broader societal shifts toward recognizing the rights and dignity of all individuals, irrespective of race or ethnicity.