The reasons the United States wrote and proposed the declaration of independence is listed in the main body, located by the grievances. However, in summary, Enlightenment thinkers such as John Locke, Voltaire, and Montesquieu gave people light and hope of their own self worth. England was raising major taxes and trampling on the human rights, proposed by John Locke. Overall, England was raising major taxes, and treating the colonies unfairly.
Farmers of the late 19th century did not benefit from the "McKinley Tariff," since this only made certain foreign goods more expensive by placing a general tax on their import.