Nice, we need more of that! I scoured the internet looking for USA made tools, can't afford them unless someone has budget suggestions.
Proto tools will tell you on their website what is made in the USA. Not sure where the material comes from but most likely the SBD "Global Materials". most likely the cheapest for US built mechanic tools.
Channellock pliers are likely going to be the cheapest US made pliers you will find. not the prettiest like Klein but will save some $$$. The Pliers use 100% USA made steel as well. Acetate Screwdrivers are pretty decent as well. They make the only pair of USA made welding pliers (welpers).
Wright tool will likely be the best bet for a true MADE in America tool set. They are all made in Ohio with steel supplied from 3 mills in Ohio. No blanks or forgings made over seas. Cougar Pro tools are from Taiwan but no Wright branded tools are. Only issue with Wright is they do lack a bit in Metric and specialty tools. SK makes up for what Wright doesn't have but they seem to be the same or a bit more in cost.
Vaughn (they own dasco punches) and Estwing hammers and prybars (estwing prybars come from taiwain) are made in Illinois and use US steel.
Wilde makes a good set of USA made punches in Kansas that are fairly priced.
Stride tool / imperial make a bunch of USA made low cost wire strippers and I think that they make a bit of the automotive tools that SK and few others sell (hose clamp pliers, ect)