What was the primary effect of the 16th Amendment in the United States?

The primary effect of the 16th Amendment was to allow the federal government to collect an income tax. Ratified in 1913, this amendment was significant because it provided a consistent source of revenue for the government, which was increasingly needed for its expanding functions and responsibilities. Prior to the amendment, income taxes were often considered unconstitutional as they were not uniform across states, and the government relied heavily on tariffs and excise taxes for funding. The adoption of the 16th Amendment marked a shift in how the federal government financed its operations, laying the groundwork for a more progressive taxation system that could be adjusted based on individuals' income levels. This ability to tax incomes ultimately played a crucial role in funding government programs and responding to economic crises throughout the 20th century.