Back in the day, local banks could print currency, and some of the bills printed in GR are still out there.

I stumbled across a web site selling 'Grand Rapids currency' and was puzzled about it. Did Grand Rapids once have a Federal mint?

Not quite.

According to the web site Antique Money, the Grand Rapids National Bank did print its own National Bank Notes for awhile during the Great Depression:

The National Bank Of Grand Rapids in Michigan printed $767,665 dollars worth of national currency. That is a high amount, but condition and serial numbers can make otherwise common currency from this bank quite valuable. This national bank opened in 1933 and stopped printing money in 1935, which equals a 3 year printing period. That means that money from this bank was not entering circulation very often. During its life, The National Bank Of Grand Rapids issued 5 different types and denominations of national currency. We have examples of the types listed below. Your bank note should look similar. Just the bank name will be different.

National Bank notes were fairly common up until World War II. According to Wikipedia:

National Bank Notes were United States currencybanknotes issued by National banks chartered by the United States Government. The notes were usually backed by United Statesbonds the bank deposited with the United States Treasury.

National Banks in Grand Rapids also printed bills going back as far as the Civil War. Those are much rarer and difficult to find.

Some of these bills are available on auction sites like eBay and Heritage Auctions. Their value varies depending on the condition of the bills.

Here's a few examples of Grand Rapids National Bank Notes.

Heritage Auctions