“One of the great weapons of a democracy.”

This was how Harry Belafonte, the performer and civil rights activist, referred to the street march in a recent interview. Mr. Belafonte played a critical role in organizing the 1963 March on Washington, which helped spur the passage of two major civil rights bills. He is also a co-chairman of the women’s march set for Saturday.

When thousands of women converge on Washington this weekend, they will join a long tradition of rallies in the capital. From the suffrage processions of the early 20th century to the Tea Party rallies of 2009, marches have drawn attention to crucial issues, occasionally resulted in violence and often prompted opposing gatherings.

Marian B. Mollin, an associate professor at Virginia Tech who studies the history of social movements, said successful marches had capitalized on symbolism and street theater, attracted a broad coalition and pushed clear policy goals.

But the test of a march’s long-term efficacy, she said, is whether it energizes participants long after they’ve gone home, sustaining them through the less exciting aspects of change. This is what she’ll be watching for in the months after Saturday’s march.