Looks like they can still dig for a while ...
Lots of salt mined around south east Lake Huron.
Goderich Ontario
https://www.compassminerals.com/who-we-are/locations/goderich-ontario/
I live a few miles from the Morton Salt Plant at Grand Saline Salt Dome. They have mined down to 750’ and say they can continue for 20,000 years. And this is just one salt dome in Texas. There are hundreds from Texas to Mississippi.
https://www.icr.org/article/does-salt-come-from-evaporated-sea-water
https://www.icr.org/article/salt-deposits-confirm-pre-flood-pangaea
https://crev.info/2019/08/geolocal-changes-rapid/
https://crev.info/2016/06/dead-sea-drying/
https://creation.com/world-s-oldest-salt-lake-only-a-few-thousand-years-old
https://creation.com/sea-salt-loses-its-savour-for-evolutionists
An old water well driller known to one of my relatives mentioend that any well deeper than 50’ west of the hamlet of Nunica will be salt water. It’s been down there a long, long time. Deeper still is the Marshall Sandstone, with plenty of water, but it’s pretty hard water.