I recently attended a wedding in Jefferson City and made it by the Missouri Governor’s Mansion. It’s a beautiful example of Second Empire architecture.
Here is a detail of the front porch of the house. Most typical of Second Empire architecture is the Mansard roof, which is the two roof system, one at a steep pitch usually punctured by windows, and a second gently pitched roof on top. Invented in 17th Century France, it is common throughout St. Louis, and much of America.
BTW, the house in Alfred Hitchcock’s movie “Psycho” is built in the Second Empire style, with some Italianate details.