JACKSONVILLE, FLA. — ON a long car trip there are always two realities at work.The first is the mind's-eye movie of the trip, the easy cinema of what we see and where we see it flowing by. The second is the intermissions, all the stops to eat, to sleep, to fill the gas tank, to photograph or be charmed by the natives and the local geography. Without question Route 1 is one great democratic movie you won't ever see on a major interstate. For color, begin with the pastels of Florida architecture, move to the red earth of southern Georgia, the gray-green of a WPA bridge, then back to the green and blue of the Maine shore; then to the peach and plum hues of the staggering number of shopping malls multiplying everywhere like the mad brooms in Disney's Fantasia. Along one 10-mile stretch of Route 1 there were 33 shopping malls. Published in Princeton, N.J., a newspaper named "U.S. 1" is filled with ads from malls and shopping centers. Banners and flags blaze from the lots of auto dealers all along the route in big and small towns. Every other one has a huge American flag billowing over a sea of Japanese cars. All this next to furniture stores, mattress stores, gas stations, McDonald's, Burger King, Wendy's, and little cafes offering "good food for the whole family." A shopping mall in Maine has a store announcing "Walk-In Bankruptcy and Divorce." Here and there you can find the cracked, weeded-over pavement of old Route 1 off to the side of the road where a curve has been smoothed or eliminated. Sometimes there are old billboards exclaiming Route 1 as the king of roads, or a hubcap store with 2,000 used hubcaps laying around like giant silver dollars suggesting that at one time many cars shot by this spot with parts flying. A bumper sticker on a car proclaims: "My daughter is an honor student at Nelson Elementary School." On a pickup truck full of sponges a bumper sticker pokes fun at feminists: "The more I learn about women, the better I like my truck." And there are the junk dealers and junk collectors in rural towns, the smell of cows and earth; there are the neat, little cottage motels built in the 1930s with skeleton keys to open wooden doors. Thirty-five dollars a night and fluffy towels. No telephones. Route 1 alternates between the extremes of two-lane rural and six-lane urban. At night it is splashed with neon in big towns and warmed with light bulbs in the hamlets where the one gas station closes at seven but leaves a sign burning in the dark: "Beer, Gas, Movies." A good Route 1 breakfast is easy to find. Look for a small, homey cafe with at least three pickup trucks parked in front, the sign that local people eat there. Sit down with the smell of fresh coffee and rolls in the air; check the plastic menu and go for the blueberry pancakes or the oatmeal or the omelet and the large glass of cold, pulpy orange juice. The waitress is brown-haired Emily or Sarah in jeans with her heart on her sleeve; she smiles, asks you where you're from, listens to your reason for being there and says, "You mean to tell me you two guys are getting paid to travel up and down Route 1?" Yes, yes, but this odyssey is not as easy as it looks, lady. After the breakfast intermission, we are in the car and the movie is rolling again... .