Website Availability in United States
Submarine cables, ISP health and blocking risks that decide whether a website loads in United States. Checked against live measurement data.
Wondering whether a website is down for everyone or just unreachable from United States? The answer usually hides in the physical layer of the internet. United States 🇺🇸 connects to the global network through 117 submarine cable systems that come ashore at 168 landing stations, and its national domain zone is .us. Every request from a user in United States to a foreign server, and every request from abroad to a site hosted in United States, physically travels over these systems or their terrestrial backhaul.
This page summarizes what our measurement network knows about internet connectivity in United States: which cables serve the country, how its leading internet providers are performing, and what can make a website appear offline for users there while it works everywhere else.
Current connectivity status in United States
As of our latest hourly measurement cycle, the national internet signal of United States is operating normally (BGP visibility and active probing dip: 0.1% against the 24-hour baseline). National-level signals catch large events; an individual website can still be unreachable for local reasons, which is what the availability checker above is for.
Connectivity for most users in United States is provided by a small group of networks:
| Provider | ASN | Share of users | Status |
|---|---|---|---|
| COMCAST-7922 - Comcast Cable Communications, LLC | AS7922 | 17.5% | No recent anomaly |
| ATT-INTERNET4 - AT&T Enterprises, LLC | AS7018 | 12% | No recent anomaly |
| CELLCO-PART - Verizon Business | AS6167 | 7.5% | No recent anomaly |
| T-MOBILE-AS21928 - T-Mobile USA, Inc. | AS21928 | 7.3% | No recent anomaly |
| CHARTER-20115 - Charter Communications LLC | AS20115 | 5.3% | No recent anomaly |
If a website fails to load only for customers of one of these providers, the problem is almost always local: DNS resolution inside that network, ISP-level filtering, or a routing issue, rather than the website itself being down.
Submarine cables that connect United States to the internet
The following systems land in United States. Cable length is a rough proxy for how much of the world a system reaches: long trunks connect continents, short ones link neighbors. Our monitors registered no significant latency anomalies on these systems in the last 30 days.
| Cable system | Length | In service since |
|---|---|---|
| Project Waterworth | 50,000 km | n/a |
| Southern Cross Cable Network (SCCN) | 30,500 km | 2000 |
| South America-1 (SAm-1) | 25,000 km | 2001 |
| GlobeNet | 23,500 km | 2000 |
| Tata TGN-Pacific | 22,300 km | 2002 |
| Bulikula | 21,600 km | 2026 |
| Pacific Crossing-1 (PC-1) | 21,000 km | 1999 |
| Asia-America Gateway (AAG) Cable System | 20,000 km | 2009 |
| Bifrost | 19,888 km | 2025 |
| Asia Connect Cable-1 (ACC-1) | 19,000 km | 2028 |
| Trans-Pacific Express (TPE) Cable System | 17,968 km | 2008 |
| America Movil Submarine Cable System-1 (AMX-1) | 17,800 km | 2014 |
Plus 105 more systems, mostly regional links. Live health data for every cable is available on the linked pages.
How resilient is United States to cable failures?
With 117 cable systems across 168 landing stations, United States has one of the most redundant internet connections in the world. Traffic can reroute across many independent systems, so a single cable fault rarely affects end users. Repairs at sea typically take one to several weeks, because a specialized cable ship has to locate the fault, lift the cable and splice it on deck.
Why a website may not load in United States
When a site works in other countries but fails in United States, the usual suspects are, in order of likelihood: a DNS problem inside a local ISP, a content delivery network misrouting users in United States to an unhealthy edge node, a routing or peering issue between local networks and the site's host, and finally a submarine cable incident affecting the whole region.
Our DNS measurements have not flagged systematic national filtering in United States, although individual ISPs and corporate networks can still block specific resources.
Neighbors on the same cables
These countries share submarine cable systems with United States, so a major cable incident can affect them together:
🇯🇵 Japan (11 shared) · 🇦🇺 Australia (9 shared) · 🇬🇧 United Kingdom (8 shared) · 🇧🇷 Brazil (8 shared) · 🇲🇽 Mexico (8 shared) · 🇵🇭 Philippines (7 shared)
See the full list on the website availability by country hub.
Frequently asked questions
How do I check if a website is down in United States?
Enter the URL into the free Global Availability Checker on this site. It compares measurement data from 80+ countries, including probes relevant to United States, and shows in seconds whether the site is down everywhere or only unreachable from specific regions.
How many submarine cables connect United States?
United States is served by 117 submarine cable systems landing at 168 coastal stations. The longest systems are Project Waterworth, Southern Cross Cable Network (SCCN), South America-1 (SAm-1).
Why does a website work in other countries but not in United States?
The most common causes are DNS failures inside a local ISP, CDN edge problems, routing issues between United States and the hosting network, national filtering, and submarine cable faults. Testing the URL from multiple countries immediately narrows down which one it is.
Who are the largest internet providers in United States?
The leading networks by user share are COMCAST-7922 - Comcast Cable Communications, LLC, ATT-INTERNET4 - AT&T Enterprises, LLC, CELLCO-PART - Verizon Business. Together they carry the majority of consumer traffic, so a problem inside any of them affects a large share of users in United States.
Can a single cable failure disconnect United States?
No. With 117 independent cable systems, traffic reroutes automatically around a single fault.
Does United States block websites?
We have not detected systematic national filtering in United States, but individual ISPs and corporate networks can still block specific sites.
Data: GeoCables submarine cable telemetry, RIPE Atlas measurements, IODA national signals, APNIC user estimates. Numbers refresh automatically; last update July 11, 2026.