The 45th parallel north is a circle of latitude that is 45 degrees north of the Earth's equatorial plane. It crosses Europe, Asia, the Pacific Ocean, North America, and the Atlantic Ocean. The 45th parallel north is often called the halfway point between the Equator and the North Pole, but the true halfway point is actually 16.2 kilometres (10.1 mi) north of the 45th parallel because the Earth is oblate, that is, it bulges at the equator and is flattened at the poles.
At this latitude the sun is visible for 15 hours, 37 minutes during the summer solstice and 8 hours, 46 minutes during the winter solstice. The midday sun stands 21.6 degrees above the southern horizon at the December solstice, 68.4 degrees at the June solstice, and exactly 45.0 degrees at the two equinoxes.
Starting at the Prime Meridian and heading eastwards, the parallel 45° north passes through:
In North America, the 45th parallel roughly marks the Canada–US border between the United States and Canada between the St. Lawrence and Connecticut rivers (the northern borders of the U.S. states of New York and Vermont with the Canadian province of Quebec), where the parallel is sometimes called the "Canada line". The actual boundary of Vermont lies approximately 1 kilometre (3,300 ft) north of the parallel due to an error in the 1772 survey. The boundary here intersects Lake Champlain, which is shared by the two nations, with most of the lake lying in the United States.
The 45th parallel makes up most of the boundary between Montana and Wyoming. It also passes through the U.S. states of Oregon, Idaho, South Dakota, Minnesota, Wisconsin, Michigan, New York, Vermont, New Hampshire and Maine and through the Canadian provinces of Ontario, Quebec, New Brunswick and Nova Scotia.
The parallel roughly bisects mainland Nova Scotia. Halifax is approximately 40 km (25 mi) south of the parallel.
All of mainland New Brunswick lies north of the 45th parallel. The southernmost point in mainland New Brunswick, just north of the 45th parallel, is Greens Point, approximately 90 kilometres (56 mi) west of Saint John. Approximately two-thirds of Deer Island, plus all of Campobello and Grand Manan islands, are south of the 45th parallel.
In Michigan, the Old Mission Peninsula in Grand Traverse Bay ends just shy of the 45th parallel. Many guidebooks and signs at the Mission Point Lighthouse describe it as being halfway between the equator and north pole. When the Grand Traverse Bay recedes below normal level, it is possible to walk out to the exact line.
Farther west, the line roughly bisects the metropolitan area of Minneapolis-St. Paul. In Minneapolis there is a marker in Theodore Wirth Park. In the Western United States, the parallel passes through the Great Plains and Rocky Mountains, intersecting the Pacific coast in Oregon. Throughout the United States the parallel is marked in many places on highways by a sign proclaiming that the location is halfway between the North Pole and the Equator.
In North America, the 45th parallel intersects or slightly bypasses (from west to east):
Continuing west, the parallel passes over vast stretches of the North Pacific Ocean before passing through Rishiri-Rebun-Sarobetsu National Park and the adjacent town of Horonobe on the northern tip of Hokkaidō, the northernmost of Japan's main islands. It continues through the northern part of the Sea of Japan, entering the Asian mainland on the coast of Primorsky Krai in Russia, north of Vladivostok.
At Khanka Lake it enters northeast China, cutting across Heilongjiang and continuing through part of Jilin and eastern Inner Mongolia. Transecting southern Mongolia it passes through the provinces of Sükhbaatar, Dornogovi (and its capital Sainshand), Dundgovi, Övörkhangai, Bayankhongor, Govi-Altai, and Khovd. In northwest China it passes through the Ili Kazakh Autonomous Prefecture in Xinjiang and the oil city of Karamay.
The parallel passes through southern Kazakhstan, intersecting the city of Burylbaytal at the southern tip of Lake Balkhash and the city of Qyzylorda further west. At the border with Uzbekistan it bisects the Aral Sea and its toxic Vozrozhdeniya Island peninsula, site of an abandoned Soviet bioweapons laboratory. It skirts the northern edge of the Ustyurt Plateau, entering back into Kazakhstan before cutting across the northern tip of the Caspian Sea and into Europe and Russia.
In Europe the 45th parallel stretches between the Caspian Sea coast of the Russian Caucasus in the east and Bay of Biscay coast of France in the west. In Russia it runs from the west coast of the Caspian Sea to the east coast of the Black Sea, through the Republic of Kalmykia, Stavropol Krai and its capital Stavropol, and Krasnodar Krai and its capital Krasnodar. In Ukraine it crosses the Crimea and its capital Simferopol.
Further west it passes through the Balkans: Romania (just north of Ploieşti, and through Târgu Jiu), the Serbian autonomous province of Vojvodina, the eastern tip of Croatia, the northern edge of Bosnia and Herzegovina, and a section of Adriatic Croatia. The capital city of Serbia – Belgrade is just south of the parallel.
In northern Italy it parallels the river Po, near Rovigo, passing by Voghera, then just south of Turin before passing into France in the Cottian Alps.
In France, it crosses the river Rhône at Pont-de-l'Isère, just north of Valence, Drôme and through Grenoble. It then continues across the Massif Central and into the Aquitaine region. The city of Bordeaux is just south of the parallel.