Purple state. (n.d.). In YourDictionary. Retrieved from https://www.yourdictionary.com/purple-state
(plural purple states)
(US, idiomatic) Somewhat whimsical synonym for swing state. (In the modern United States) a state that may support the Democratic or Republican Party (purple states, states that vote for Democratic or Republican Party in general, being red states in some given elections and blue states in other given elections).
English Wiktionary. Available under CC-BY-SA license.