United States
Northern America · 22 specs
Direct Answer
The United States (US / USA / 840) operates on a 120 V / 60 Hz electrical grid using NEMA 1-15 (Type A) and NEMA 5-15 (Type B) sockets. Traffic drives on the right (RHT). The official currency is the US Dollar (USD, $), country calling code is +1 (exit code 011), emergency services are reached at 911, and the primary document format is US Letter (8.5 × 11 in).
Source: ANSI / ISO 3166-1 / National Electrical Code (NFPA 70) / US Postal Service · Last reviewed Aug 28, 2026
Specs
| Official English Name | United States of America ISO 3166-1 |
| Local Endonym | United States of America |
| ISO 3166-1 Alpha-2 | US |
| ISO 3166-1 Alpha-3 | USA |
| ISO 3166-1 Numeric / UN M49 | 840 UN M49 (Code 021) |
| Country Calling Code | +1 NANP (ITU-T E.164) |
| International Exit Code (IDD) | 011 dial prefix for international calls |
| Internet ccTLD | .us (.com, .gov, .edu, .mil) IANA Standard |
| Vehicle Registration Code | USA UNECE 1949/1968 Convention |
| National Currency (ISO 4217) | United States Dollar (USD, $) 100 Cents (¢) |
| Mains Electricity Standard | 120 V (±5%), 60 Hz ANSI C84.1 / NFPA 70 (NEC) |
| Electrical Plug Sockets | Type A (NEMA 1-15) & Type B (NEMA 5-15) 15 A / 125 V rating |
| Heavy Appliance Electricity | 240 V Split-Phase, 60 Hz NEMA 14-50 / NEMA 10-30 |
| Road Traffic Driving Side | Right-Hand Traffic (RHT / LHD) Standard US rules |
| Primary Measurement System | US Customary (Inches, Feet, Pounds, °F) NIST Handbook 44 |
| Standard Office Paper Format | US Letter (8.5 × 11 in / 215.9 × 279.4 mm) ANSI/ASME Y14.1 |
| Standard Business Envelope | #10 Commercial (4.125 × 9.5 in / 104.8 × 241.3 mm) USPS Standard |
| Consolidated Emergency Number | 911 Police, Fire, Ambulance dispatch |
| Postal Code Regex / Format | 5 Digits (ZIP) or 5+4 (ZIP+4: NNNNN-NNNN) USPS Standard |
| Primary Time Zones (Continental) | UTC-5 (EST) to UTC-8 (PST) 6 zones total (inc. AKST, HAST) |
| Date Format Standard | MM/DD/YYYY (e.g., 08/23/2026) Traditional standard |
| Number Radix / Separators | $1,234.56 (Comma thousands, Dot decimal) US Standard |
US Customary Units Policy & The 1975 Metric Transition
The United States is one of only three countries globally (alongside Myanmar and Liberia) that has not officially adopted the International System of Units (Metric SI) as its primary daily measurement system:
- The Metric Conversion Act (1975): Declared metrication voluntary, leading American industry to maintain dual systems: Metric for science, military, electronics, and automotive manufacturing, alongside US Customary (inches, feet, pounds, gallons, °F) for consumer retail, construction, and road navigation.
Electrical Grid, Voltage & Plug Compatibility
- Nominal Grid Parameters: Operates on a single-phase standard of 120 V (±5%), 60 Hz.
- Plug & Socket Hardware: Type A (NEMA 1-15) & Type B (NEMA 5-15). Uses North American style Type A (2-blade ungrounded) and Type B (3-prong grounded) receptacles.
- International Traveler Guidance: Devices operating on 100–240 V (smartphones, laptops) require only a mechanical pin adapter. Single-voltage appliances from differing voltage regions require a certified step-down/step-up power transformer.
Telecommunications, Dialing & Emergency Dispatch
- International Dialing: The country calling code is +1. Outbound international calls from within the country require dial prefix 011 followed by the destination country code.
- Emergency Dispatch: Consolidated emergency services are reached at 911. Calls are automatically routed to local public safety answering points with emergency vehicle dispatch.
Transportation, Driving Standards & Road Regulations
- Traffic Flow: Road traffic drives on the right (RHT) with Left-Hand Drive (LHD) vehicles.
- Standard Speed Limits: General regulatory speed limits default to 50 km/h (31 mph) in built-up urban and residential zones, 80–100 km/h (50–62 mph) on undivided rural roads, and 110–130 km/h (68–81 mph) on grade-separated divided motorways/expressways (unless lower local limits are posted).
- Safety Requirements: Mandatory seatbelt compliance for all occupants, zero-distraction handheld mobile phone bans while driving, and mandatory in-vehicle warning triangles.
Commerce, Currency & Document Standards
- Official Currency: Legal tender is the United States Dollar (USD, $).
- Document & Paper Standards: Standard office printing, official government gazettes, and legal filings strictly utilize US Letter (8.5 × 11 in / 215.9 × 279.4 mm). Standard business correspondence pairs with standard business envelopes.
- National Time Zone: Regulated under Standard time.
Postal Addressing & Administrative Divisions
- Postal Architecture: Postal delivery utilizes 5 Digits (ZIP) or 5+4 (ZIP+4: NNNNN-NNNN).
- Standard Address Format: Structured in standardized hierarchy: Recipient Name → Street Address / Building Unit → Postal Code + City/Town → Province/State → United States of America.