Here's proof that companies are actually using .us. This is a start and there's much more room for growth as companies realize the value of targeting the us market specifically by using the country code.
Go to http://www.google.com and run the following searches:
inc -gov -state -mil -lib -org site:.us
us inc -gov -state -mil -lib -org site:.us
Also go to http://www.yahoo.com and run the following search:
intitle:inc -gov -org -mil -state -edu -lib site:.us
Go to http://www.google.com and run the following searches:
inc -gov -state -mil -lib -org site:.us
us inc -gov -state -mil -lib -org site:.us
Also go to http://www.yahoo.com and run the following search:
intitle:inc -gov -org -mil -state -edu -lib site:.us