N.Y. State Law § 5
The boundary line between the state of New York and Canada is as follows:
Commencing at the intersection of the parallel of the forty-fifth degree of north latitude with the middle of the deepest channel of the Richelieu river and running thence westerly along said parallel of forty-five degrees north latitude as originally run by Valentine and Collins, 1771-1774, to a point on the south shore of the St. Lawrence river (but shown by the United States survey of boundary line in 184 5, under treaty of Washington, 1842, on sheet maps XXVI to XXX to vary from true parallel of forty-five degrees, as follows: monument 645, on bank of Richelieu river, is .822 miles north of parallel of 45° and .02 miles west from river; thence westerly 14.68 miles to monument 673, at .336 miles north; thence westerly 6.56 miles to monument 685, at .353 miles north; thence westerly 9.20 miles to monument 703, at .004 miles south; thence westerly 7.43 miles to monument 717, at .429 miles south; thence westerly 10.02 miles to monument 737, at .475 miles south; thence westerly 6.34 miles to monument 749, at .140 miles south; thence westerly 88 miles to monument 762, on true parallel of 45°; thence westerly 4.20 miles to monument 774, at .030 miles north on bank of St. Lawrence river S. 74° 45' W. 1840 yards distant from the stone church in the Indian village of St. Regis, this line being recognized as the boundary line by article one of said treaty of Washington). Thence beginning at aforesaid point on the south shore of the Saint Lawrence river, marked by monument 774, under the treaty of Washington, 1842, and in 1817 by a stone monument erected by Andrew Ellicott (the location of which point is described above), and running north 35° 45' west into the river, on a line at right angles with the southern shore, to a point 100 yards south of the opposite island, called Cornwall island; thence turning westerly and passing around the southern and western side of said island keeping 100 yards distant therefrom, and following the curvatures of its shores, to a point opposite to the northwest corner or angle of said island; thence to and along the middle of the main river until it approaches the eastern extremity of Barnhart's island; thence northerly along the channel which divides the last mentioned island from the Canada shore, keeping 100 yards distant from the island, until it approaches Sheik's island; thence along the middle of the strait which divides Barnhart's and Sheik's islands to the channel called the Long Sault, which separates the two last mentioned islands from the lower Long Sault island; thence westerly (crossing the center of the last mentioned channel) until it approaches within 100 yards of the north shore of the Lower Sault island; thence up the north branch of the river keeping to the north of and near the Lower Sault island, and also north of and near the Upper Sault, sometimes called Baxter's island, and south of the two small islands marked on the map A and B, to the western extremity of the Upper Sault or Baxter's island; thence passing between the two islands called the Cats, to the middle of the river above; thence along the middle of the river, keeping to the north of the small islands marked C and D, and north also of Chrystler's island, and of the small island next above it, marked E, until it approaches the northeast angle of Goose Neck island; thence along the passage which divides the last mentioned island from the Canada shore, keeping 100 yards from the island to the upper end of the same; thence south of and near the two small islands called the Nut islands; thence north of and near the island marked F, and also of the island called Dry or Smuggler's island; thence passing between the islands marked G and H to the north of the island called Isle au Rapid Platt; thence along the north side of the last mentioned island, keeping 100 yards from the shore, to the upper end thereof; thence along the middle of the river, keeping to the south of and near the islands called Coussin (or Tussin) and Presque isle; thence up the river, keeping north of and near the several Gallop Isles numbered on the map, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, and also of Tick, Tibbits, and Chimney islands, and south of and near the Gallop isles numbered 11, 12 and 13, and also of Duck, Drummond, and Sheep islands; thence along the middle of the river, passing north of island No. 14, south of 15 and 16, north of 17, south of 18, 19, 20, 21, 22, 23, 24, 25 and 28, and north of 26 and 27; thence along the middle of the river, north of Gull island and of the islands Nos. 29, 32, 33, 34, 35, Bluff island, and Nos. 39, 44 and 45, and to the south of Nos. 30, 31, 36, Grenadier island, and Nos. 27, 28, 40, 41, 42, 43, 46, 47 and 48 until it approaches the east end of Wells island, thence to the north of Wells island, and along the strait which divides it from Rowe's island, keeping to the north of the small islands Nos. 51, 52, 54, 58, 59 and 61, and to the south of the small islands numbered and marked 49, 50, 53, 55, 57, 60, and X, until it approaches the northeast point of Grindstone island; thence to the north of Grindstone island and keeping to the north also of the small islands Nos. 63, 65, 67, 68, 70, 72, 73, 74, 75, 76, 77 and 78, and to the south of Nos. 62, 64, 66, 69 and 71, until it approaches the southern point of Hickory island; thence passing to the south of Hickory island and of the two small islands lying near its southern extremity numbered 79 and 80; thence to the south of Grand or Long island, keeping near its southern shore, and passing to the north of Carlton island, until it arrives opposite to the southwestern point, of said Grand island, in Lake Ontario; thence, passing to the north of Grenadier, Fox, Stony, and the Gallop islands, in Lake Ontario, and to the south of and near the islands called the Ducks, to the middle of the said lake, thence westerly along the middle of said lake to a point opposite the mouth of the Niagara river, thence to and up the middle of the said river to the Great Falls; thence up the Falls through the point of the Horse Shoe, keeping to the west of Irish or Goat island, and of the group of small islands at its head, and following the bends of the river so as to enter the strait between Navy and Grand islands; thence along the middle of said strait to the head of Navy island; thence to the west and south of and near to Grand and Beaver islands, and to the west of Strawberry, Unity, and Bird islands to Lake Erie; thence southerly and westerly along the middle of Lake Erie in a direction to enter the passage immediately south of Middle island, being one of the easternmost of the group of islands lying in the western part of said lake (according to the decision of the commissioners under the sixth article of the treaty of Ghent, 1814, done at Utica, state of New York, June 18, 1822) to intersection with meridian line of Cession, drawn through the most westerly bent or inclination of Lake Ontario, under deed of cession to the United States, executed March 1, 1781, under chapter thirty-eight of the third session of the legislature of this state in 1780, which meridian line was surveyed and marked with monuments by Andrew Ellicott in 1790, as duly appointed under resolution of Congress, August 19, 1789, and resurveyed in 1881 to 1885, and final report made December 1, 1885, by H. W. Clarke, civil engineer and surveyor, on the part of the state of New York.
N.Y. State Law § 5