The northern industrial states of the United States, including Ohio, Michigan, and Pennsylvania, in which heavy industry was once the dominant economic activity. In the 1960s, 1970s, and 1980s, these states lost much of their economic base to economically attractive regions of the United States and to countries where labor was cheaper, leaving old machinery to rust in the moist northern climate. The manufacturing region in the United States is currently debilitated because many manufacturing firms have relocated to countries offering cheaper labor and relaxed environmental regulations.