That is difficult to say without some caveats in these days of Globalization.
Do you mean American Made with American Parts (SVS uses Canadian Made Plate Amps), American Assembled with all Imported parts, American Designed with parts and Assembly outsourced, etc etc. You see what I mean.
What Paul said—it is pretty hard to know where each component is sourced. Plus the sourcing often varies from run to run.
ACI has a reputation of being an American-made company. I know for sure that their very excellent cabinetwork is done in the US—except for the ELT system. I have no direct knowledge of where they source their components.
There are plenty of US-based, custom speaker companies—many of them one or two man shows. Once again it is difficult to know where they source their components.
Vandersteen, Thiel, some Infinity, some JBL, McIntosh, M&K, Merlin, Martin-Logan, Boston Acoustics, Phase Technology among others. That said, most good drivers come from Scandinavia (Denmark, Norway).
Some Boston speakers are made overseas. Same goes for some NHTs. Polks are made in Mexico, and same with some JBL. Although you would be surprised that some Pioneer speakers are designed and build in the US.
For myself I plan to buy some comercial JBL drivers and crossovers and build a custom enclosure for them. This is all to match a custom center and rears to my american made A-7 Altec Lancing Voice Of The Theater speakers. I will at that point build custom dual JBL 18" subs
Crowded Public Theaters, Who Needs A Stinkin Croweded Public Theater
It's amazing the performance you get with very inexpensive drivers these days from places such as Taiwan. I have a pair of BIC America DV-604 bipolar towers and a pair of DCM CX-27 and a pair of CX-17 monitors and all of the drivers are made in Taiwan and obviously low cost. But they have suprisingly good sound and the DV-604s go deep - below 30Hz.
These inexpensive drivers can sound really good in a properly designed cabinet.
I have to correct you on this one, Brett Frank. Phase Technology is entirely manufactured in their Jacksonville, FL facility. All cabinets, drivers and their components, and crossovers are produced in this facility. They wind their own voice coils and crossover parts in house. I just wanted to clarify this. They are one of the few TRUE American made speaker manufacturers.
As a matter of fact, the Altec Lansing "Voice of the Theater" speakers Dave Moritz speaks about contain drivers manufactured by Phase Tech's parent comapany: United Speaker Systems.
I believe you are also incorrect saying McIntosh has parts made ovrseas. Don't quote me on that, they might these days, but not in the early days.
Cabinet and crossover design are critical. In the 80's, John Dunlavy had a company called Duntech (in Australia) that made two very high quality wall mounted speakers (the PCL3 and PCL5) that Bert Whyte raved about in Audio magazine. These used the Audax TW010E1 which costs around $6. Driver cost doesn't always equate finished product goodness (or lack thereof).
Well, aren't most of the Klipsch speakers made in Arkansas? I'm pretty sure their reference speakers are are still made there. (Well, ASSEMBLED in AR. might be a better way to put it)
When I purchsed my Def Tech BP2002's in '97 they were made in U.S. When I bought the CLR 2002 in '02 i was disappointed to see MADE IN CHINA on the box.
For the record; with the exception of the ELT, all ACI cabinets are made in one of three shops within a 40 mile radius of La Crosse. Crossovers are built here in La Crosse from U.S. and European parts. Subwoofer amps are manufactured for us here in the U.S. Subwoofer drivers are manufactured in California, with most of the other drivers being Scandinavian. All final assembly, testing, and packaging is done here in La Crosse.
FWIW: In my experience, there are many quality vendors and suppliers around the globe. Point of origin doesn't necessarily indicate quality or lack of.