Where are sunflowers habitat?

Answer 1

Department of Agronomy
Of all crops harvested for seed around the world, only one was domesticated in America - sunflower. This widely adapted crop is now grown in every temperate region, including many parts of the U.S.
In the U.S., 2.7 million acres were grown in 1991, about 85 percent of which was oilseed sunflower. The rest was grown for whole-seed confectionary uses. North Dakota has been the leader in sunflower production, with 1.4 million acres in 1991. South Dakota and Minnesota are the next biggest sunflower producers.
Kansas grew about 75,000 acres of sunflower in 1991, about two-thirds of it oilseed varieties. Nearly 20,000 acres were grown in Missouri in the late 1970s, but Missouri acreage declined to a few thousand acres after prices fell. The 1990 Farm Bill has renewed interest in sunflower, since it established new farm programs to promote sunflower and other minor oilseeds


Wikipedia (slightly abridged) says:
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The sunflower is native to the Americas. The evidence thus far is that it was first domesticated in Mexico, by at least 2600 BC. It may have been domesticated a second time in the middle Mississippi Valley, or been introduced there from Mexico at an early date, as maize (corn) was. The earliest known examples of a fully domesticated sunflower north of Mexico have been found in Tennessee and date to around 2300 BC.