Why Do We Say White Collar and Blue Collar?

How did blue collar, white collar (and pink collar!) end up in our lexicon, and what are the origins of their meanings?

Globally, Men, White-Collar Workers Upbeat on Job Market

Blue-Collar vs White-Collar Jobs

The origins of white collar vs. blue collar - ADP ReThink Quarterly

The differences between white collar job hunting and blue collar

White Collar vs. Blue Collar - Meaning & Difference

Are the Terms “White Collar” and “Blue Collar” Problematic?

Why flexibility means freedom to blue- and gray-collar workers

Blue-collar worker - Wikipedia

Consolidation Case Study: Enhancing Operations in Blue Collar Back

Culture & Traditions, HowStuffWorks