Delaware and Maryland.
Aleutian Islands
Michigan is the US state divided into two large parts, the Upper Peninsula and the Lower Peninsula. The Upper Peninsula is not physically attached to the Lower Peninsula and is separated by the Straits of Mackinac.
The Iberian Peninsula mainly contains the countries of Spain and Portugal. The US has large populations of both Spanish and Portuguese. The Iberian Peninsula is where Hispanics originate from, and the US has a large Hispanic population. Spain has also owned part of what is now the US (mainly the Western US, Florida, Puerto Rico, and Guam). The US and Iberian Peninsula also used to be psychically connected to each other some 500-200 mya when they were both a part of Laurasia.
The Iberian peninsula.
Peninsula is a noun.
The Gulf of California separates the Baja California Peninsula from most of the rest of Mexico. Note that the peninsula is NOT part of the US state of California. It is part of Mexico.
The Aleutian IslandsThe Aleutian Islands.
Balkan peninsula
The Kamchatka Peninsula is part of Russia. It juts out into the Pacific.
The Arabian Peninsula is part of the Middle East and Asia.
A peninsula is a piece of land sticking out into a body of water. In the US, one of the most notable is Point Roberts, a part of Washington to which you can only get by going through British Columbia. ( or by sea) - Better known perhaps is Ocean Park Peninsula at the south west corner of Washington.