Markets / East-West Corridor
The East-West Corridor along I-88 is the largest suburban office market in the Chicago area, about 75 million SF from Oak Brook west to Naperville and the Fox Valley. As of October 2026, about 14% of that space sat vacant, about 18% in Class A buildings, and the corridor absorbed about 200,000 SF over the past year. The two ends are moving in opposite directions: vacancy is about 17% on the eastern end around Oak Brook and Downers Grove and about 11% on the western end around Naperville and Lisle. In the transactions we track and negotiate, Class A space along the corridor leases for about $39 per SF gross and Class B for about $26, with 1 to 1.5 months of free rent per year of term and improvement allowances of $6 to $8 per SF per lease year. Tenant Advisors represents only tenants.
The two ends of the corridor are moving in opposite directions, and that decides where your leverage is. The figures below combine the eastern corridor (Oak Brook, Oakbrook Terrace, Downers Grove and the I-294 end) with the western corridor (Lisle, Naperville and west to the Fox Valley).
| October 2026 | East-West Corridor, combined | Eastern corridor (Oak Brook, Downers Grove) | Western corridor (Naperville, Lisle) |
|---|---|---|---|
| Office inventory | About 75.5 million SF | About 36 million SF | About 40 million SF |
| Overall vacancy | About 14%, down from about 15% a year ago | About 17%, roughly flat | About 11%, down from 12% a year ago |
| Class A vacancy | About 18% | About 16%, down from 18% | About 21% |
| Class B vacancy | About 16% | About 20%, up from 19% | About 12%, down from 13% |
| Net absorption, last 12 months | About +200,000 SF | About +68,000 SF | About +132,000 SF |
| New construction underway | About 80,000 SF, all single-story | About 65,000 SF (medical) | About 15,000 SF |
| Sublease space available | About 460,000 SF | About 220,000 SF | About 240,000 SF |
| Lease terms we are negotiating | Class A | Class B |
|---|---|---|
| Rent, gross per SF | About $39 | About $26 |
| Free rent | 1 to 1.5 months per year of term | 1 to 1.5 months per year of term |
| Improvement allowance | $6 to $8 per SF per lease year ($30 to $40 on a 5-year lease) | $3 to $6 per SF per lease year ($15 to $30 on a 5-year lease) |
| Free rent on a 5-year lease | Typically 5 to 7½ months | Typically 5 to 7½ months |
Rents and concessions reflect the East-West Corridor transactions Tenant Advisors tracks and negotiates as of October 2026. Results vary by building, size, term, and credit. About 1.2 million SF of older office space has been removed from the corridor over the past five years, most of it on the western end, and about 1.2 million SF of new office space has been proposed, including a 351,000 SF tower in Oak Brook.
Overall vacancy is improving, but the two ends of I-88 and the two building classes are moving in different directions.
It absorbed about 200,000 SF over the past year, and vacancy eased from about 15% to about 14%. The western end accounted for about 132,000 SF of that gain.
Vacancy around Oak Brook and Downers Grove is about 17% and roughly flat, and eastern Class B vacancy rose to about 20%.
Western vacancy is down to about 11%, but about 21% of its Class A space is empty, the highest of any segment on the corridor.
About 1.2 million SF of older office space has been removed over the past five years, most of it on the western end, and only about 80,000 SF of single-story space is under construction.
About 21% of western-corridor Class A space is vacant. Several Class A campuses along Diehl Road, Warrenville Road, and Shuman Boulevard have a quarter to nearly half of their space empty, and those landlords are competing hardest.
Eastern-corridor Class B vacancy is about 20% and still rising, the reverse of the western end. Older Butterfield Road and 22nd Street buildings are where landlords are most flexible on rate and concessions.
Class B vacancy in Naperville, Lisle, and Warrenville is about 12% and falling, and older buildings keep coming off the market. If you want well-priced Class B space on the western end, start 12 to 18 months before your lease expires.
About 460,000 SF of sublease space is available along the corridor, much of it built out and furnished. For short terms or fast moves, it can cut both cost and time. And a renewal should be priced against all of it, not just your landlord’s asking rate.
The tenants most active along the East-West Corridor right now are:
Three properties that shape pricing along I-88. Figures are October 2026 and rounded.
The corridor’s tallest office building, about 792,000 SF. Seven leases totaling about 58,000 SF were signed in the past year, and about 23% of the building is vacant, so large blocks are still on the table.
About 263,000 SF at I-88 and Highland Avenue. One 140,000 SF lease in the past year was the largest Class A move-in on the corridor and accounts for much of the eastern end’s gain.
About 312,000 SF on Warrenville Road, about 21% vacant, with three leases signed in the past year. A 243,000 SF third phase is proposed next door, which would be the largest new office building on the western corridor.
We don’t represent any of these landlords. Ask us which buildings fit your size, budget, and term, and what they are actually conceding.
A recent East-West Corridor lease. The client’s name is withheld; the numbers are not.
Many of the brokers working the East-West Corridor also lease buildings for landlords here. Tenant Advisors has represented only tenants since 2004 and doesn’t own or manage office buildings, so every building along I-88 is on the table and every landlord is someone we negotiate against.
As of October 2026, about 14% of office space along the I-88 East-West Corridor was vacant: about 17% on the eastern end around Oak Brook and Downers Grove and about 11% on the western end around Naperville and Lisle. Class A vacancy was about 18% and Class B about 16%. Figures are rounded Tenant Advisors Market Data.
In the transactions we track and negotiate as of October 2026, Class A office space along the East-West Corridor leases for about $39 per SF gross and Class B for about $26. Building quality, size, term, and credit move the final number.
Typically 1 to 1.5 months of free rent per year of lease term, or about 5 to 7½ months on a 5-year lease, plus improvement allowances of $6 to $8 per SF per lease year in Class A and about $3 to $6 in Class B. Tenants who create competition between buildings get the upper end.
It depends on building class. In Class A, the western end around Naperville and Lisle has more empty space, about 21% against about 16% in the east. In Class B, the eastern end around Oak Brook and Downers Grove has more, about 20% against about 12% in the west.
About 460,000 SF along the corridor, about 220,000 SF on the eastern end and about 240,000 SF on the western end, much of it built out and often furnished.
For most tenants, yes. About one in seven square feet is vacant and landlords along I-88 are competing for tenants. The exception is western Class B, where vacancy is about 12% and falling, so tenants who want well-priced Class B space in Naperville, Lisle, or Warrenville should start 12 to 18 months before their lease expires.
Oak Brook, Oakbrook Terrace, Downers Grove, Lombard, Elmhurst, Westmont, Hinsdale, and Burr Ridge on the eastern end, and Lisle, Warrenville, Naperville, Wheaton, Aurora, and St. Charles on the western end.
Updated October 17, 2026, with October 2026 Tenant Advisors Market Data. Written by Tom Koelzer and Dave Ven Horst, co-founders of Tenant Advisors, Inc., in Chicago office leasing since 1986 and 1985 and tenant-only since 2004. Our office: 1515 E. Woodfield Road, Suite 116, Schaumburg, IL 60173.
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