PITTSBURG, N.H. -- It begins at the roof of New Hampshire, and you can be there.
The Connecticut River, New England's biggest and arguably most significant, flows 410 miles from its northern tip up here near the Canadian border south to Long Island Sound. Along the way, it forms the border between two states, shares its name with a third, and was instrumental in the history, culture, and commerce of much of the region. It begins in what the Nature Conservancy, which shepherds the area, refers to somewhat unromantically as a ''northern acidic mountain tarn."
That would be the Fourth Connecticut Lake. From Pittsburg north, the first three lakes stretch out, becoming increasingly smaller as they head toward Canada. Straddling the Canadian border in this land of many moose is the fourth and smallest of the four, where, in a rich, green spruce and fir forest valley, the river starts its journey.
Unlike First, Second, and Third Connecticut Lakes, which can be seen from ''Moose Alley," or Route 3 in Pittsburg, and which lure boaters and anglers with easy access points, Fourth Connecticut Lake is bigger than a puddle and is accessible only by foot.
A 1.7-mile hike around the lake begins at an odd place, just behind the US Customs Station at the border, where a trailhead has a place for hikers to sign in and get a map. The launching point is also an end point of the 170-mile-long Cohos Trail, which runs from Hart's Location in Crawford Notch to the border.
This is no long-distance schlep, but rather a roughly two-hour scamper. More than a walk through the woods, the hike has a couple of steep pitches in its initial leg and is thick with plant growth along trail's edge.
Boundary markers embedded in rock are frequent along the trail before it reaches the lake. Hikers can straddle the border and not one tree will ask for identification. A few signs on the Quebec side warn visitors (in French) that should they venture farther, they are on private property.
The lake itself isn't all that spectacular, rather more like a pond. Roots, downed trees, and mud are the round-the-lake path obstacles, but they're easily navigated.
At the southern end of the lake, the Connecticut River begins. Jump across the water or walk stone by stone.
It is here, up in the northern wilds, where the river that belongs to almost all of New England begins its journey between New Hampshire and Vermont and through Massachusetts and Connecticut. Its waters were once a thoroughfare for log drives and the mills of another age. And you'll be able to say you were there at the beginning.
Marty Basch is a freelance writer in New Hampshire.