I remember going to the Sunset Drive-In as a child in Helena, Mont., with my parents, who would fold down the back seats of our station wagon and have sleeping bags and pillows laid out for us. My dad would clean the windshield with Windex and newspapers before we left the house. Even though my mom would bring a picnic basket full of snacks, we’d still walk down to the concession stand to get popcorn in a paper bucket the size of a milk pail, the salty kernels swimming in butter.