FLORIDA!
Yes it is.
Florida.
Honolulu
Florida.
If the question actually means the 48 contiguous US States then it is Florida. Na'alehu Hawaii is the southernmost town in the US and Hawaii is the southernmost US State.
Country? ...or did you mean state?
Key West, Florida for the contiguous States and the Big Island of Hawaii for the US States.
Hawaii is the southernmost state of the USA.
Honolulu is the capital of the US state of Hawaii. Hawaii (known officially as Hawai'i) is the only state outside of the North American continent and also the southernmost state of the United States.
Florida: The Florida Keys is the most southern point in the United States.
The furthest point south in the continuous US is in the Florida Keys at approximately 24.521075 latitude at the southern tip of Ballast Key. However, the furthest north the Hawaiian islands reach is the northernmost point of the island of Kaua'i at latitude 22.22969.