The Meduxnekeag River, a tributary of the St. John River, rises in two principal branches in Aroostook County in the State of Maine (which contains about 3/4 of its total watershed) and ends in New Brunswick where it joins the St. John in downtown Woodstock.
The North and South branches cross the border separately and join just below Jackson Falls on the South Branch, then flow approximately 25 km to the mouth at Woodstock.
In New Brunswick, the watershed of the Meduxnekeag is home to the richest, most diverse, and highest concentration of remnant sites of mature Appalachian Hardwood Forest in Atlantic Canada. This forest type, also known as St. John River Valley Hardwood, contains many understorey plants rare or uncommon in the province. These include black raspberry, wild ginger, maidenhair fern, showy orchis, wild coffee, and numerous others.
Significant sections of the Meduxnekeag are easy to canoe or kayak in high or medium water conditions (generally in May and June, and in September and October; also in July/August in wet summers). Annual canoe races are held in both Maine and New Brunswick in May. In New Brunswick, recreational canoeists traditionally put in below McBride Bridge on the North Branch (just above the confluence) and take out in downtown Woodstock, a half-day canoe trip depending on lingering time, passing through scenic, mostly forested country. The final 2 km before Woodstock is through an extensive wetland. Walking trails on the Meduxnekeag Valley Nature Preserve are accessible from the river below Red Bridge.
The intervales and islands of the Meduxnekeag are locally celebrated for the edible fiddlehead (ostrich fern), harvested in May.
The Meduxnekeag is the only New Brunswick river with a resident population of brown trout. Parts of the river are fly fishing only; other sections are hook-and-release. Some of the best small mouth bass fishing in eastern North America can be found at the mouth of the Meduxnekeag and nearby parts of the St. John.