Obviously, you're not allowed to detonate fireworks in a national park. However, the law also prohibits park visitors from having fireworks in their possession at any time during their stay.
Is smoking allowed in Yellowstone National Park?
Permitted: Smoking inside vehicles, on sidewalks, in gravel or paved parking areas, in developed campgrounds, immediately adjacent to backcountry fire rings, and in designated smoking areas inside buildings. In addition, smoking is not allowed on trails and in thermal areas.
Is smoking allowed in Yosemite National Park?
In Yosemite National Park in California, below 6,000 feet in elevation campfires are not permitted beyond designated campgrounds and picnic areas. Additionally, smoking is only allowed in designated areas, inside a vehicle, or at campgrounds where fires are allowed.