Final answer:
False, Union Course was a horse racing track, not a facility built for baseball and football games; significant baseball parks like Fenway Park in Boston were built later.
Step-by-step explanation:
The statement that The first significant sport facility built in the United States was Union Course, built for baseball and football games is false. Union Course was a significant horse racing track in Queens, New York, established in the early 19th century, and was not built for baseball and football games. The history of sport facilities in the United States is complex, but significant sport facilities built specifically for baseball include Fenway Park in Boston (1912) and Forbes Field in Pittsburgh (1909). Moreover, the first college football game dates back to 1869, while the first professional baseball team, the Cincinnati Red Stockings, was established in 1869. Baseball rapidly grew in popularity, culminating with the founding of the National League in 1876. Though Union Course was important, its legacy does not primarily lie in baseball or football but in horse racing.