They range from the Kuskokwin River in Alaska to the Rio Santo Domingo in Baja California. Rainbows are closely related to Redband and the Golden Trout.
Rainbows are entirely fresh water fish.
The steelhead trout, a close relative to the rainbow, is the anadromous version. It lives in the Pacific ocean and migrates up into the streams of the west coast to spawn. Their migration can be a 1000 or more miles. The rainbow trout characteristically are very colorful with an overall metallic coat. They have a bright red coloration on the gill covers with deep pink band down the lateral line.