Area codes in Decatur, Illinois

Decatur, Illinois uses 2 area codes — 217 and 447. The main Decatur area code is 217.

Area codes serving Decatur

Phone numbers in Decatur are written as ten digits — for example (217) 555-0190 — and fall in the Central Time zone.

How Decatur came to have 2 area codes

The original Decatur area code is 217, in service since 1947. As the area ran low on available numbers, an overlay code was added over the same region for new phone lines: 447 (2021). Existing numbers kept their original code — an overlay never forces anyone to change their number — which is why Decatur now uses all 2 codes and every local call is dialed with ten digits.

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Frequently asked questions

What is the area code for Decatur?

The main area code for Decatur, Illinois is 217. Decatur is now served by 2 area codes in total: 217, 447.

How many area codes does Decatur have?

Decatur has 2 area codes: 217, 447.

Why does Decatur have more than one area code?

As Decatur used up the numbers available in its original area code (217, in service since 1947), additional "overlay" codes were added over the same area so new phone numbers could keep being assigned.

How do you dial a Decatur number?

Dial all 10 digits — the area code (217 or 447) followed by the 7-digit local number. From abroad, dial +1, then the area code and number.

Sourced from the official NANPA (North American Numbering Plan Administrator) numbering database, current as of August 2, 2026. Refreshed monthly.