Dennis Tangney Jr./Getty Images

Take a seafood road trip along U.S. Route 1.

New England's Memorial Bridge, with its classic steel uprights and industrial design, serves its very practical purpose well: carrying U.S. Route 1 over the Piscataqua River, the watery boundary separating New Hampshire and Maine, while offering some picturesque views along the way. But for food-lovers in the know, this bridge holds a deeper purpose, acting as the conduit between two under-the-radar culinary powerhouses on the brink of national fame.

 Enna Grazier

Start out south of the Piscataqua in Portsmouth, New Hampshire: There, stalwart Black Trumpet Bistro has been serving its signature seafood paella for 10 years, while Portsmouth Brewery recently celebrated 26 years of pulling pints. While both still warrant a visit (and be sure to pick up one of Black Trumpet's signature spice blends at its adjacent shop, Stock + Spice), Portsmouth has far more to show. On the beer front, quirky nanobrewery Earth Eagle Brewings specializes in a style of hop-free beers called "gruits," flavored with mystical-sounding herbs like yarrow and coltsfoot. (If hopheads are in tow, head instead to new IPA specialist Great Rhythm Brewing Company, located in the city's West End.)

 Morgan Ione Photography

Two oyster bars, meanwhile, are located a shell's throw from one another: Grab a luxe, bountiful lobster roll at the local outpost of Boston favorite Row 34, and hit Franklin Oyster House for modernized oysters Rockefeller and buttery, briny "The Franklin" bivalves on the half shell, cultivated exclusively for the restaurant by nearby Bay Point Oyster Company.

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But for all those urban charms, the biggest culinary arsenal might lie on the north side of the bridge, in Kittery, Maine. In the center of the Piscataqua on Badger's Island, stop at Blind Pig Provisions for duck fat–fried toast with roasted tomatoes, best savored from a perch on a red Adirondack chair overlooking the water.

 Courtesy of Anju Noodle Bar/Misty Kinser

From there, skip the tourist-laden outlet malls and make a beeline for the slice of downtown known as Wallingford Square, where spots like Lil's Cafe and Anju Noodle Bar possess an Instagram-chic varnish less visible in laid-back Portsmouth. And the goods—like the former's custardy French crullers and the latter's delicate white kimchi, which can be purchased to go—back up the aesthetics. Sample the best of Maine and New Hampshire beers, including those from nearby Tributary Brewing Company, at The Black Birch gastropub. Don't worry if there's a wait: The adjacent art gallery is a welcome amuse-bouche.

Still have some culinary stamina? Grab a nightcap at the Wallingford Dram, and be sure to polish off your second cruller (did we mention you'll need multiples of those?) on the ride home.

Leah Mennies is a Boston-based food writer.