Parks being popular domestic destinations means they get crowded – especially in the summer months. Parks in all regions of the country become notably packed when kids are not in school, so opt to visit during one of the “shoulder” seasons (typically late spring or early fall). You’ll also experience more pleasant temperatures during those months, specifically in destinations where the weather can be dangerously hot in the summer, like Arizona’s Grand Canyon and Utah’s Zion National Park. If summer is your only option, look into whether you can book tickets to parks and attractions in advance. It’ll save you time.