I'm a bit confused on how this would work. My cousin's farm originally belonged to my great uncle. It's been a working farm, in our family, for nearly 150, if n

I'm a bit confused on how this would work. My cousin's farm originally belonged to my great uncle. It's been a working farm, in our family, for nearly 150, if not more. So if the 150 years has passed, does he need to vacate the farm? My uncle currently lives on my grandfather's farm, and that has been in our family for the same amount of time. Neither of these people are very wealthy. This type of thing is pretty common where I grew up. Middle class people inherit working farms and continue working them.