.US is another country code top-level domain. As the name suggests it is the ccTLD for the United States. The .us domain was created in 1985 and is operated by GoDaddy. There are more than 1.5 million domains registered with the .us extension.
Requirements to register .US domain
Unlike some other ccTLDs the .us domain cannot be registered by anyone. To register this ccTLD you must be a citizen, resident, organization, or foreign entity that is somehow affiliated with the United States. If you meet these criteria and you would like to register a .us domain you can do that from the page here.