Today's know a union job: Great Lakes Mariner
Biggest unions: American Maritime Officers (AMO) for licensed officers and Searfarers International Union (SIU) for unlicensed positions.
Common conditions (contact details change depending on the company using the unions): Position on a freighter servicing the Great Lakes dry commodity needs. This includes ore, stone, coal, grain, sand, salt and other goods.
Freighters come in different sizes and needs, but a typical 22-23 person crew will have 8 officers and 14-15 unlicensed crew.
A typical sailing season lasts 270-280 days a year. A full time mariner will sail approximately 200 days. Vessel operations does not stop for weekends, nights or holidays. A typical stay on a vessel would be 45, 60 or 90 days straight followed by approximately a month off before returning for another tour.
Unlicensed can join the SIU without experience, though they also offer an apprentice program. Licensed cadets come from a number of sources including SUNY Maritime College and Great Lakes Maritime Academy.
A children's book called "Mail by the Pail" was written by a current mariner to explain this unique way of life and is available on Amazon (No, it is not my book.).