Final answer:
The Dallas Cowboys is the highest-valued sports franchise in the history of America, with an estimated value of $6.5 billion.
Step-by-step explanation:
The highest-valued sports franchise in the history of America is the Dallas Cowboys football team. As of 2021, the Dallas Cowboys have an estimated value of $6.5 billion, making them not only the most valuable sports franchise in America, but also in the world. The team's value comes from its success on the field, its brand recognition, and its massive fanbase.