Glaciers were in what is now the U.S., what 12k years ago?
The area encompassed by the State of Indiana has several series of glacial terminal moraines. These are the piles of debris left at the edge of a retreating glacier.
The Indiana Moraines reflect SEVERAL of the ancient glaciations and extend from about Indianapolis all the way to Louisville.
There's also a highlands area in the middle that tends to confound everyone's thoughts about the glaciers.
One of the things we don't know much about yet are the various interstadials that occur in the midst of a glaciation. These are warming periods that last less than 10,000 years and are not as widespread as the interglacials that last at least 10,000 years.
It is possible that due to a slight uptick in the GW process about 3,000 BC we now have an interglacial that's latched onto an early interstadial. Because of that it is entirely possible the next glaciation could start tomorrow ~ which is just 1 hour and 42 minutes away.
Up to 16000 years ago, per the Visitor’s Center in Yosemite NP last weekend.
Sorry, that is when the glaciers COVERED the USA. 16,000 years ago. We still had glaciers in the lower 48 just a few thousand years ago.