"Toponyms" just means "place names." You can read about them in the book Place Names of Washington, by Robert Hitchman.
Place Names
Mill Valley, California is an associative Toponym.
There is only one Washington state ... and yes, Seattle is in Washington state.
Washington has the nickname "Evergreen State"
Washington State.
Washington state
The State of Washington.
Washington state used to be a territory (Washington territory) before it became a state. But then on Nov. 11 1889 Washington became an official state. So now Washington is a state and not a territory.
Because they named Washington state after George Washington
no, Washington is the 42nd state
Washington doesn't have states in it if you are talking about Washington State.
Olympia is the state capital of Washington