When the relative pronoun is the object of a preposition, which is used instead of that, for example,  in which ,  for which ,  about which ,  through which , etc. (please see the third example below): Formal English: This is the man to whom I wanted to speak and whose name I had forgotten.he relative pronoun that can only be used in restrictive clauses. It can also be substituted for who (referring to persons) or which (referring to things) in informal English. Whereas that is often used while speaking, who and which are more common in formal written English.
For other uses, see Yellowstone (disambiguation). Yellowstone National Park is a national park located in the U.S. states of Wyoming, Montana and Idaho. It was established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872. Yellowstone was the first National Park in the U.S. and is also widely held to be the first national park in the world.
National Parks & Monuments. This year, the National Park Service is celebrating its 100th anniversary. And it just so happens, Wyoming is home to the very first National Park: Yellowstone. Plus, we have the first National Monument: Devils Tower. In total, the state boasts an impressive 25 National Historic Landmarks and 11 nationally recognized recreation areas, trails and monuments. It goes without saying that this celebration is a pretty special one for our scenery.