Genzink Plumbing, Holland, Mich., opened its doors in 1961; five years later, the company hired Melvin Vander Zwaag and he’s been there ever since.
In fact current owner Ross Genzink was just a 1-year-old when his father hired Vander Zwaag.
At the age of 72, Vander Zwaag is semi-retired, working about three days a week.
More details here.
Source: Holland Sentinel