According to Encyclopedia Britannica, nonimportation agreements were economic measures used to force Britain to recognize the political rights of the U.S. colonies in the 1760s. These agreements were initiated in reaction to the Stamp Act of 1765 and the Townshend Act of 1767.
Nonimportation agreements alarmed British merchants because of the mass-scale boycotts of English goods that followed. When merchants alerted the British Parliament, it repealed the Stamp and Townshend Acts. These actions ended the boycotts but led to the creation of nonimport and nonexport committees. These entities all represented colonial unity, which groups like the Sons of Liberty and Whig merchants helped to enforce.
According to US history.org, the Continental Congress created The Association in 1774, which duly placed a colonial ban on any trade with Britain. Experts note that the trade value of American imports dropped significantly between 1772 to 1774. In addition British manufacturers were alarmed at the growing trend of domestic production of goods that were previously purchased from Britain.
Despite these efforts, Encyclopedia Britannica notes that in the late 1700s, Britain developed new markets around Europe. The economic effects that colonists counted on for 10 years did not prevail. American trade embargoes also reappeared in the 19th century when Congress passed the Nonimportation Act, which banned certain English goods in an attempt to force Britain to respect American naval operations.