Actual Number of States in the United States of America: 50 States
The United States of America (USA) sometimes shortened as United States (U.S.) or just America is composed of 50 states and a federal district (Washington, D.C). The USA also has a number of unincorporated territories. These include islands such as Puerto Rico, Guam, and American Samoa to name a few. The states are represented as stars on the flag. The last state (50) to be added was Hawaii in 1959.
Remembering that the US has 51 or 52 states is a common Mandela Effect, seemingly from people even living in the US, although if the responses are to be believed online, it appears as though this misconception is generally coming from non-US residents. I first heard about about it on the Mandela Effect website.