Final answer:
The statement that NAFTA could only become law in the U.S. after ratification by the U.S. Senate is true. After negotiations and additional agreements for worker and environmental protections, it was ratified in late 1993 and took effect in 1994.
Step-by-step explanation:
The treaty known as the North American Free Trade Agreement (NAFTA) could indeed only become law in the United States after being ratified by the U.S. Senate. This statement is true. The treaty aimed to eliminate tariffs and trade restrictions among the United States, Canada, and Mexico. Negotiated by President George H. W. Bush, the leaders of all three nations signed it in December 1992. However, it faced opposition, including from American labor unions. President Clinton added agreements to protect workers and the environment to help address these concerns, which led to Congress ratifying NAFTA in late 1993, and the treaty went into effect in 1994, creating one of the world's largest common markets.