or plumber, vocational training or apprenticeships are required and state-certification is also necessary. For this reason, it is common to apply the label "blue collar" or "working class" to people without a college education, whether or not they work in a blue-collar job. Blue collar shift to developing nations With the information revolution, Western nations have moved towards a service and white-collar economy. Many manufacturing jobs have been offshored to developing nations which pay their workers lower wages. This offshoring has pushed formerly agrarian nations to industrialized economies and concurrently decreased the number of blue-collar jobs in developed countries. In the U.S., blue collar and service occupations generally refer to jobs in precision production, craft, and repair occupations; machine operators and inspectors; transportation and moving occupations; handlers, equipment cleaners, helpers, and laborers. In the U.S., an area known as the Rust Belt comprising the Northeast and Midwest, including Western New York and Western Pennsylvania, has seen its once large manufacturing base shrink significantly. With the de-industrialization of these areas starting in the mid-1960s, cities like Cleveland, Ohio; Detroit, Michigan; Buffalo, New York; Pittsburgh, Pennsylvania; Erie, Pennsylvania; Youngstown, Ohio; Toledo, Ohio; Rochester, New York; and St. Louis, Missouri have experienced a steady decline of the blue-collar workforce and subsequent population decreases. Due to this economic osmosis, the rust belt has experienced high unemployment, poverty, and urban blight. Automation and future Due to many blue-collar jobs involving manual labor, automation poses a threat of unemployment for blue-collar workers. One study from the MIT Technology Review estimates that 83% of jobs that make less than $20 per hour are threatened by automation. Some examples of technology that threaten workers are self-driving cars and automated cleaning devices, which could place blue-collar workers such as truck drivers or janitors out of work. Others have suggested that technological advancement will not lead to blue-collar job unemployment, but rather shifts in the types of work performed. Proponents of this idea view coding as a replacement for blue-collar jobs, and suggest that more coders will be needed in a technologically advancing world, and posit that, ostensibly, new white-collar IT jobs could be filled by displaced blue-collar workers. Others see future of blue-collar work as humans and computers working together to improve efficiency. Adjective Blue-collar can be used as an adjective to describe the environment of the blue-collar worker or a setting reflective of that environment, such as a