Lake County, Illinois

Lake County is a county in Illinois, United States, about 35 miles north of downtown Chicago along the western shore of Lake Michigan. It had a population of 714,342 at the 2020 census, an estimated 719,339 by 2025, and its 444 square miles of land (1,150 km2) sit centred near 42°26′N 87°47′W. A further 925 square miles of Lake Michigan is apportioned to the county line, bringing the Census Bureau’s total area to 1,368 square miles (3,540 km2) — more water than land, a distinction no other Illinois county shares.

Waukegan is the county seat; its postal code is 60085. The county holds 7 cities and 44 incorporated villages across 18 townships, and it runs on Central Time. Its FIPS code is 17097.

Towns & Villages in Lake County

Lake County has 51 incorporated municipalities — 7 cities and 44 villages — the most of any county on this site so far. Several straddle the Cook County line to the south; those are noted below. Population and ZIP are shown only where a figure comes from the 2020 census or a confirmed USPS assignment — an em dash means the number could not be verified rather than guessed.

Places marked ¹ straddle the Cook County line: Buffalo Grove is roughly three-quarters in Lake County and one-quarter in Cook, Barrington and Barrington Hills spread across Cook, Lake, McHenry and Kane counties, Deer Park sits mostly in Lake with a sliver in Cook, Wheeling is mostly a Cook County village with a small Lake County edge, and Long Grove has a small Cook County extension. Places marked ² cross into McHenry County instead: most of Fox Lake, Island Lake, Lakemoor and Port Barrington lie in McHenry, with only a share of each village’s land inside Lake County. Fox River Grove is mostly in McHenry and Cook counties, with a small unincorporated edge reaching into Lake.

Townships

ZIP Codes

• 60085 & 60087 — Waukegan (also serves Park City)
• 60031 — Gurnee
• 60035 — Highland Park
• 60040 — Highwood
• 60045 — Lake Forest
• 60044 — Lake Bluff
• 60015 — Deerfield (also serves Bannockburn and Riverwoods)
• 60069 — Lincolnshire
• 60061 — Vernon Hills (also serves Indian Creek and Mettawa)
• 60048 — Libertyville (also serves Green Oaks)
• 60060 — Mundelein
• 60030 — Grayslake
• 60073 — Round Lake (also serves Round Lake Beach, Round Lake Park and Round Lake Heights)
• 60046 — Lake Villa and Lindenhurst
• 60002 — Antioch
• 60020 — Fox Lake
• 60041 — Ingleside
• 60084 — Wauconda (also serves Island Lake, Lake Barrington and Volo)
• 60047 — Lake Zurich (also serves Hawthorn Woods and Kildeer)
• 60010 & 60011 — Barrington
• 60089 — Buffalo Grove
• 60099 — Zion
• 60064 & 60086 — North Chicago
• 60083 — Wadsworth (also serves Old Mill Creek)
• 60096 — Winthrop Harbor
• 60088 — Naval Station Great Lakes

Beach Park, Deer Park, Bannockburn’s outlying edges, Long Grove, Tower Lakes, North Barrington, Port Barrington, Lakemoor and several of the smallest villages have no ZIP of their own and are served entirely by a neighbouring town’s post office; that is noted above rather than guessed at.

Geography

Lake County sits on flat to gently rolling glacial moraine country left behind by the Wisconsin glaciation, cut through by the Des Plaines River and the Fox River’s Chain O’Lakes system in the county’s northwest corner. Its eastern edge is the Lake Michigan shoreline — bluffs at Highland Park and Lake Forest, beaches at Waukegan and at the Illinois Beach nature preserve near Zion. Water covers a larger share of the county’s Census-defined area than any other Illinois county once Lake Michigan is counted; on dry land, the Chain O’Lakes and Long Lake dominate the northwest.

Lake County borders Kenosha County, Wisconsin to the north, Cook County, Illinois to the south, and McHenry County, Illinois to the west (no live townsvillages.com page for McHenry County, Illinois yet); Lake Michigan forms its entire eastern boundary.

Demographics

Lake County had a population of 714,342 at the 2020 census, the third-largest of any Illinois county, and an estimated 719,339 residents by 2025. Waukegan and Mundelein are its two largest communities. The county’s population density is about 1,610 people per square mile of land. Median household income runs above the Illinois state figure, driven by affluent North Shore communities such as Highland Park, Lake Forest and Deerfield, while Waukegan, North Chicago and Zion post the county’s lowest median incomes and its most diverse populations.

Economy & Local Life

Naval Station Great Lakes, the U.S. Navy’s only recruit training command, sits mostly within North Chicago and is the county’s single largest employer presence, training about 40,000 recruits a year across a 1,628-acre installation. Waukegan itself is anchored by Lake County government offices (about 2,400 workers), Southwire’s cable-manufacturing plant, Vista Medical Center East and Medline Industries. Mundelein’s employers include Medline Industries’ corporate operations, Ruprecht Company meat processing and the University of Saint Mary of the Lake seminary. Deerfield is Walgreens’ corporate headquarters town, and Lincolnshire hosts Camping World and Zebra Technologies’ headquarters. Gurnee’s economy leans on tourism: Six Flags Great America and its water park draw roughly 3 million visitors a year, and Gurnee Mills, the fourth-largest mall in Illinois, adds millions more.

History

The Illinois General Assembly created Lake County in 1839 out of the northern part of McHenry County, naming it for Lake Michigan. Libertyville (then called Burlington) served as the first county seat before it moved to Little Fort, renamed Waukegan, in 1841. Waukegan’s own name comes from the Potawatomi word for “fortress” or “trading post,” replacing the earlier French-derived “Little Fort.” The city grew as a 19th-century industrial port, drawing Scandinavian and southeastern European immigrant labor into shipbuilding, flour milling and pork packing. Zion has a stranger origin: evangelist John Alexander Dowie founded it in 1900 as a theocratic community built around his Christian Catholic Apostolic Church, personally owning nearly all the land and businesses in its early decades; the city’s religious code enshrined a literal flat-earth doctrine until the 1940s. Naval Station Great Lakes opened in 1911 and became the Navy’s sole boot camp after 1990s base closures shut comparable facilities in San Diego and Orlando.

Getting There

Interstate 94 (the Tri-State Tollway) runs north–south through the county’s eastern third, connecting to Interstate 41 near the Wisconsin line; U.S. Route 41 and U.S. Route 12 carry most north–south and east–west local traffic elsewhere. Four Metra commuter lines — the Union Pacific North, Union Pacific Northwest, Milwaukee District North and North Central Service — connect county stations to downtown Chicago.

• Chicago Loop — 35 miles south via Interstate 94 or the Union Pacific North Line
• Milwaukee, Wisconsin — 45 miles north via Interstate 94
• Elgin — 20 miles west via U.S. Route 20
• Rockford — 70 miles west via Interstate 90

Waukegan National Airport handles general aviation inside the county; the nearest major commercial airport is Chicago O’Hare International, about 30 miles south, with Milwaukee Mitchell International also within reach to the north. Amtrak’s Hiawatha service and long-distance trains are reached via Chicago Union Station, connected by Metra.

Frequently Asked Questions

Where is Lake County, Illinois?
It is in the northeastern corner of Illinois, along the western shore of Lake Michigan, bordered by Wisconsin to the north and Cook County to the south.

What is the population of Lake County?
714,342 at the 2020 census, an estimated 719,339 by 2025 — the third-most populous county in Illinois.

How big is Lake County?
444 square miles of land (1,150 km2); the Census Bureau’s total figure of 1,368 square miles also counts 925 square miles of Lake Michigan apportioned to the county.

What is the county seat of Lake County?
Waukegan, population 89,321, postal code 60085.

How many towns and villages are in Lake County?
51 incorporated municipalities — 7 cities and 44 villages — across 18 townships.

Which ZIP codes cover Lake County?
More than two dozen, from 60002 (Antioch) and 60010/60011 (Barrington) to 60099 (Zion); see the ZIP Codes section above for the full list.

What is Naval Station Great Lakes?
The U.S. Navy’s only recruit training command, based mostly in North Chicago, training about 40,000 new sailors a year.

More counties in this state: Towns and villages in Illinois.