The 520 area code serves Tucson and southern Arizona, the region stretching from the second-largest city in the state south to the Mexican border. Created in 1995 when it split from 602, 520 covers a large desert region rich in astronomy, aerospace, and mining.
Quick Summary of the 520 Area Code
| Area Code | 520 |
| State | Arizona (AZ) |
| Region | Southern Arizona (Tucson) |
| Major Cities | Tucson, Sierra Vista, Casa Grande, Oro Valley, Marana, Green Valley, Nogales, Douglas |
| Time Zone | Mountain Standard Time (MST) – no daylight saving |
| Dialing Format | 7 or 10-digit dialing |
Geographic Coverage
The 520 area code covers southern Arizona, centered on Tucson and its suburbs of Oro Valley and Marana, and extending south to the retirement community of Green Valley, the border cities of Nogales and Douglas, the military city of Sierra Vista, and Casa Grande along the corridor toward Phoenix. It borders Mexico to the south and New Mexico to the east.
Time Zone
The 520 area code observes Mountain Standard Time (MST, UTC−7), but Arizona is unusual: it does not observe daylight saving time and keeps the same clock all year. This produces an interesting effect – in winter the region is on Mountain Time, one hour ahead of the West Coast, but in summer, when other states spring forward and Arizona does not, the 520 area effectively matches Pacific Daylight Time and shares the same clock as California.
Tip: Business hours across the 520 region generally run 9:00 AM to 5:00 PM local time, Monday through Friday.
How to Dial a 520 Number
Area code 520 is not part of an overlay, so it has traditionally allowed 7-digit local dialing. However, 10-digit dialing is now the recommended nationwide standard, and dialing the full 10-digit number (520 + the line number) always works reliably. For international callers, dial your country’s exit code, then +1 (the North American country code), then 520, followed by the seven-digit local number.
Scam Alerts for the 520 Area Code
Like every U.S. area code, 520 has been used by scammers who spoof local numbers to appear trustworthy. Residents in Tucson, Sierra Vista, Casa Grande, Oro Valley, Marana, Green Valley, Nogales, Douglas should stay alert to the following common tactics:
| Scam Type | What to Watch For |
|---|---|
| IRS / Tax Scams | Callers claiming you owe back taxes and threatening arrest unless you pay immediately. |
| Utility Shut-off | Fake Tucson Electric Power reps demanding payment to avoid disconnection in the heat. |
| Student Loan Scam | Calls offering fake loan forgiveness to University of Arizona students for a fee. |
| Bank Fraud Alerts | Robocalls impersonating your bank about “suspicious activity” to phish account details. |
If you receive a suspicious call from a 520 number, take these steps to protect yourself:
- Do not share personal information such as Social Security numbers, bank details, or passwords over the phone.
- Hang up and verify by calling the organization back using an official number from its website.
- Report the call to the FTC at reportfraud.ftc.gov and to the Arizona Attorney General’s Office.
- Block the number and consider registering with the National Do Not Call Registry.
Red Flag: Legitimate agencies such as the IRS, Social Security Administration, or your local utility company (APS, SRP, or Tucson Electric Power) will never demand immediate payment by gift card, wire transfer, or cryptocurrency. Any 520 caller making such a demand is a scammer.
History and Economy of the 520 Region
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Area code 520 was created in 1995, split from 602, to serve southern Arizona; the northern and western parts of its original territory were later carved out into the 928 area code in 2001. The regional economy is anchored by the University of Arizona, a major research institution in Tucson, and by aerospace and defense – Raytheon Missiles & Defense is one of the largest employers, alongside Davis-Monthan Air Force Base. Southern Arizona is also a world center for astronomy and optics, thanks to its clear skies and mountaintop observatories, and copper mining, healthcare, and cross-border trade through Nogales round out the economy.
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Looking Up a 520 Number
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To identify a 520 caller, use a reverse phone lookup service or search the full 10-digit number online. Many Tucson businesses, the university, and government offices list their 520 numbers publicly, so a quick search often confirms a legitimate caller. For unknown numbers, let the call go to voicemail – genuine callers usually leave a message.
Nearby & Related Area Codes
Arizona is served by several area codes. If you are researching 520, these neighboring codes are worth knowing:
- 602 – Central Phoenix
- 480 – East Valley / Scottsdale & Mesa
- 928 – Northern & Western AZ / Flagstaff
- 623 – West Valley / Glendale
You can also browse our full directory of Arizona area codes for more regional guides.
↑ See the complete list of All US Area Codes by State – every area code across all 50 states in one directory.
Explore Neighboring States
Researching area codes just across the state line? Start with these codes in the states that border Arizona:
- California – area code 213
- Nevada – area code 702
- Utah – area code 801
- Colorado – area code 303
- New Mexico – area code 505
Frequently Asked Questions
Where is the 520 area code located?
The 520 area code covers southern Arizona, including Tucson, Sierra Vista, Casa Grande, Oro Valley, Marana, Green Valley, Nogales, and Douglas.
Does 520 have an overlay?
No. The 520 area code covers southern Arizona on its own and currently has no overlay code.
Do I need to dial 10 digits for 520?
Because 520 has no overlay, 7-digit local dialing has historically worked, but dialing the full 10 digits is now the recommended standard and always works.
Does the 520 area code observe daylight saving time?
No. Like almost all of Arizona, the 520 area stays on Mountain Standard Time year-round and does not change its clocks.
Related 520 Guides
- Is a 520 call safe? Read Is area code 520 a scam? Spam & safety guide.
- Local coverage: see the Tucson area code guide.
- Worried about spam or robocalls? Browse our Scam Alerts directory.