I read before that the definition of "high blood pressure" has changed over time, and I finally wanted to find out if this is true, and if, by how much. After searching for quite a bit, I found this great chart from Medscape that show the development of the JNC definition over time. It’s clearly visible how the definition of "normal" dropped over time.
I don’t want to go into the reasons: The main question is whether we were initially wrong, or whether interest groups pushed it down. Make up your own mind.