A Continuous Lean's "American List" has a list of American-made clothing and footwear brands that still manufacture in the US. ACL's list includes Alden, Allen Edmonds, Arrow Moccasin, Quoddy, Red Wing, Wesco, White's Boots, Wesco and Wolverine. It's a very good list but not exhaustive. Here's another list of shoes made in the USA.
If country of make is important to you, perhaps an Allegiance Footwear work boot might fit the bill.
This may not be traditionally welted construction but it does look comfortable and durable.