.us
| Introduced | February 15, 1985 |
|---|---|
| TLD type | Country code top-level domain |
| Status | Active |
| Registry | Neustar |
| Sponsor | National Telecommunications and Information Administration |
| Intended use | Entities connected with  United States
|
| Actual use |
|
| Registered domains | 1,715,757 (March 2016) |
| Registration restrictions | U.S. nexus requirement can be enforced by challenge but seldom is |
| Structure | 2nd-level registrations allowed; originally only 3rd- or 4th-level registrations in a complex hierarchy |
| Documents | RFC 1480; USDoC agreements with Neustar |
| Dispute policies | usTLD Dispute Resolution Policy (usDRP) |
| Website | about.us |
| DNSSEC | yes |
.us is the Internet country code top-level domain (ccTLD) for the United States. It was established in 1985. Registrants of .us domains must be United States citizens, residents, or organizations, or a foreign entity with a presence in the United States. Most registrants in the country have registered for .com, .net, .org and other gTLDs, instead of .us, which has primarily been used by state and local governments despite any entity having the option of registering a .us domain.
On February 15, 1985, .us was created as the Internet's first ccTLD. Its original administrator was Jon Postel of the Information Sciences Institute (ISI) at the University of Southern California (USC). He administered .us under a subcontract that the ISI and USC had from SRI International (which held the .us and the gTLD contract with the United States Department of Defense) and later Network Solutions (which held the .us and the gTLD contract with the National Science Foundation).
Postel and his colleague Ann Cooper codified the .us ccTLD's policies in December 1992 as RFC 1386 and revised them the following June in RFC 1480. Registrants could only register third-level domains or higher in a geographic and organizational hierarchy. From June 1993 to June 1997, Postel delegated the vast majority of the geographic subdomains under .us to various public and private entities. .us registrants could register with the delegated manager for the specific zone they wished to register in, but not directly with the .us administrator. In July 1997, Postel instituted a "50/500 rule" that limited each delegated manager to 500 localities maximum, 50 in a given state.
...
Wikipedia