Why were the committees of correspondence powerful?

The committees of correspondence were powerful because they were the shadow governments of the Thirteen Colonies when the United States was still under the rule of the British government. Since they rallied opposition to the British government, this paved the way for a patriotic union of the thirteen colonies, which later set up the American Revolution to be independent of British rule. The committee of correspondence was the leadership of most of the communities, so there were about 8,000 patriots who served, making it a big leadership position which maintained a significant amount of power.