Final answer:
The sector of the U.S. economy that generates 70% of its value is the service sector or the tertiary sector.
Step-by-step explanation:
The sector of the U.S. economy that generates 70% of its value is the tertiary sector or the service sector. The service sector includes various industries such as healthcare, education, legal and financial services, and more. This sector makes up more than three-quarters of the US economy and is measured by its share of the gross domestic product (GDP).