How did the Montgomery bus boycott help the African American's struggle for civil rights?
The boycott helped many blacks start businesses in Montgomery.
The boycott showed that civil rights for African Americans could be easily won.
The Alabama legislature began to pass laws that quickly desegregated Alabama
society.
The Supreme Court struck down Alabama's requirement of segregation on
buses.

Literally hit them where it hurt: their pocket.

About 80% of bus users were African Americans and they encouraged each other to boycott buses. Through their combined effort and shared hardships (walked longer distances and carpooled) they eventually achieved some civil rights: the Supreme Court ruled that segregation on buses was “unconstitutional”.

This shows that civil rights could be attained through boycotts.