As of now, **Duke Energy** is one of the largest electricity companies in the U.S. based on the number of customers served. Duke Energy operates in several states and has a significant presence in the southeastern part of the country.
However, there are other major players in the U.S. electricity market as well, such as:
- **Exelon Corporation**: One of the largest energy companies in the U.S., Exelon operates several subsidiaries that provide electricity and gas services.
- **Consolidated Edison (Con Edison)**: Serving the New York metropolitan area, Con Edison is a major utility provider.
- **PPL Corporation**: Operating in various states, PPL serves millions of customers with electricity and gas.
The rankings can vary depending on the metric used, such as the number of customers, revenue, or total electricity output.