Area Code 331

Illinois (IL) • Aurora, Naperville, Bolingbrook, Downers Grove, Saint Charles, Wheaton, Addison, Batavia • Central Time (CT)

What Stands Out

•Coverage: 1.4M people across 56 ZIP codes.
•Overlapping area codes: 630.
•Major cities: Aurora, Naperville, Bolingbrook.

Spotlight: Coverage

Snapshot highlights for area code 331.

Income

90th

Home values

79th

Poverty rate

29th

Area Code Basics

Primary State

Illinois (IL)

States Served

Illinois (IL)

Major Cities

Aurora, Naperville, Bolingbrook, Downers Grove, Saint Charles, Wheaton, Addison, Batavia

Time Zone(s)

Central Time (CT)

Est. Population

1.4M

ZIP Codes

Data accuracy & methodology

This report aggregates 2020–2024 ACS 5-year estimates and geographic overlays for orientation. Area-code service areas can cross ZIP/state boundaries and change over time; verify official assignments with NANPA for critical use.