The headwaters of which American river lie closest to the border with Canada?

The Connecticut River is the correct answer because its headwaters originate in the U.S. state of New Hampshire, near the border with Canada. The river flows south through New England before eventually emptying into Long Island Sound. This proximity to the northern border makes it closest among the options provided.

In contrast, the headwaters of the Delaware River are located in the Pocono Mountains of Pennsylvania, while the Ohio River begins at the confluence of the Allegheny and Monongahela Rivers in Pittsburgh, Pennsylvania. The Colorado River, originating in the Rocky Mountains of Colorado, flows southwest towards the Gulf of California. All these rivers have headwaters that are situated much further from the Canadian border than the Connecticut River, reinforcing why the Connecticut is the most suitable choice in this context.