According to http://nj.com when The Black Horse Tavern and Pub opened in 1742, Mendham wasn’t yet a town, New Jersey wasn’t yet a state and America wasn’t yet a country.
https://www.nj.com/food/2023/10/after-281-years-does-new-jerseys-oldest-restaurant-still-hold-up-review.html: After 281 years, does New Jersey’s oldest restaurant still hold up?