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.

Starting at the Prime Meridian and heading eastwards, the parallel 45° north passes through:

In North America, the 45th parallel roughly marks the 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.

45th parallel may refer to:

Cody Willis is a fictional character from the Australian soap opera Neighbours, originally played by Amelia Frid. She made her first on-screen appearance on 24 November 1989. The character departed in 1991, but returned in 1993 with Peta Brady in the role. Cody was last seen on-screen on 29 March 1996, following her death.

Frid successfully auditioned for Neighbours in 1989 and was cast in the role of Cody. Frid called the experience a "right time, right place thing", she also added that "it was all kind of surreal". Frid decided to leave when her contract was due to end. At the same time she was also studying for her VCE. Frid said that there was a lot of interest in renewing her contract, as her on-screen family had just been introduced. However, her Principal told her that the school could not support her if she wanted to continue with Neighbours and take her VCE. Frid and Cody departed on-screen on 30 July 1991. When the character was brought back, Frid was not asked to return and producers recast and gave the role to newcomer Brady. Brady was a full time student at Sydney University when she won the role of Cody. After four years in the role, Brady decided to quit Neighbours. She said that Cody "has been great fun to play", but it was time to move on.