Of the full size tools the Leathermans and SOGs are American made. Some of the Gerbers are now Asian and all the CRKT tools and knives are Asian (they only have an office in the Portland area.
I have been to Leatherman, Gerber, SOG, Benchmade, Kershaw and CRKT. I am farmiliar with Imerpial Schrade who handed their workforce their walking papers in July 2004 and left plenty of suppliers with unpaid bills.
SOG makes nice tools although I do not own one at present. They are well made though and I would have no problem using one. Located just noth of Seattle
CRKT is Asian and I have no problem paying the money for a well made US tool. In addition you NEVER know what you are going to get when the steel comes from Asia... There address in in the Portland area, like many other cutlery people but no manufacturing is there.
Gerber Multi Tools are both American and Asian made. Check the packages. I have had a 600 which I bought for my dad and then inherited for years. It is a nice, if rather plain, multi tool most noticeable for its one handed opening pliers. They make some nice stuff and are the main quality competitor for...
Leatherman. LTG is the powerhouse of the multitools. They are very well made and the design innovations have moved forward rapidly thanks to pressure from Gerber. The two are 20 minutes from each other and people do go from one to the other. LTG is big on bringing work in house and has moved fineblanking in house as welll as numerous other operations. Some of the smaller tools are made in China but all the full sizes I know of are American assembled. I have a Crunch (locking pliers) and Black Ti Charge that I love for the one handed opening blades on the outside of the handles. It is my normal carry tool now. If in the area Leatherman has a store on premises that sells at MSRP but sometimes has specials. My black Ti Charge was $70 since the black was being discontinued. Often they will have seconds like the squirts that had a slight color variation on the panels so you can get a good deal there but don't count on finding a cataloged tool at a discount. Tim Leatherman is a granola eater who supported Kerry and signed a stupid letter to that effect which resulted in a huge backlash against his company. He then flubbed the response... I don't know so much about anti gun groups but he donated to Kerry. Given the are of the nation he is in and the amount of tree huggers that seems to be the norm.
Kershaw is owned by Kai Cutlery and also in the Portland area. They make nice stuff but like Japanese automotive want nothing to do with you if you are also not Japanese. Doesn't matter they have a plant in the US, they are Japanese through and through. As a result I do not have a Kershaw multi tool. They do not appeal to me anyway with regards to design but I would wager they are well made.
Benchmade is also in the same area. No multitools but if they did it would be a solid performer. Anything in the Blue box or better is US made. Great shop and I wish I sold them parts but they make many of their own.
I have looked at the Swiss Tools and been to Switzerland several times. The tools are well made and sturdy. They are rather plain though and I am not impressed by the features. They strike me as a desperation attempt to recapture much of the Swiss Army Knife market which fell in love with the multi tools. They seem very bulky for the job they are to do and far too overpriced compared to even high end Gerber and Leathermans made in the USA.