Because the British government was taxing them heavily.
Answer:
French + Indian War
Stamp Act
Townshend Acts
Boston Massacre
Committees of Correspondence
Boston Tea Party
Since free trade allows the business market to reach overseas outside their own nations, many business man seek to sell and cooperate with the other nation's business cooperation in order to expand their market and gain more profit. This urged the economy to become global with the economic exchange across countries.
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