Reasons the Sixteenth Amendment to the US constitution was passed by Congress in 1909 and ratified by the states in 1913 include:
1. Democrats and progressives believed the income tax to be fairer method of generating revenue than tariffs (taxes on the import and export of goods).
2. Western and southern states were concerned about commodity prices, which were impacted by tariffs, and therefore preferred an alternative means of revenue.
3. Republicans were split on whether to oppose or support amendment.