Final answer:
The service sector is the largest part of the US economy, representing more than three-quarters of its GDP, with industries like healthcare and education being notable contributors.
Step-by-step explanation:
The largest sector of the US economy is the service sector. It encompasses a range of industries, including but not limited to healthcare, education, finance, and legal services. In terms of gross domestic product (GDP), which measures the total value of all goods and services produced within a given year, services represent over three-quarters of the US economy and have been increasing their share over time. This growth indicates a significant shift from an economy based on manufacturing physical goods to one that predominantly provides services.