Both the Federal and State governments are prohibited from granting "titles of nobility" under the US Constitution (Art. 1, Sec. 9 & 10).
My understanding is that "titles of nobility" are commonly read to mean, titles (ie, special names) that are: -- inheritable -- tied to the land -- confer legal privileges -- granted by the executive authority of the relevant sovereign
My understanding of the "century farm" programs, common in many States (see https://en.wikipedia.org/wiki/Century_Farm), is that many meet all these conditions...
Are they then unconstitutional?