Community High School District 99

It never has a ZIP Code to itself

At 1,559 homes to the square mile this is city territory, and district lines in a city follow streets. Community High School District 99 covers 31 square miles in all — small enough that a single ZIP Code area can hold most of it, and several ZIP Codes can cut across it.

• Homes inside the boundary48,154
• Residents112,178
• ZIP Code areas it reaches11
• Where it is the only district0
• Where it shares with another district8
• Where it holds under half a percent3
• Land area31 square miles
• Homes per square mile1,559

The ZIP Code areas it reaches

The spread is the thing to notice. In 60516 this district holds 95% of the homes; in 60540 it holds 1 home, under half a percent. Same district, opposite answers, and a lookup that names it without the share tells the second household the same thing as the first.

• ZIP Code 60516 · Downers Grove, Illinois95% of the homes
• ZIP Code 60517 · Woodridge, Illinois93% of the homes
• ZIP Code 60515 · Downers Grove, Illinois93% of the homes
• ZIP Code 60559 · Westmont, Illinois46% of the homes
• ZIP Code 60561 · Darien, Illinois34% of the homes
• ZIP Code 60523 · Oak Brook, Illinois20% of the homes
• ZIP Code 60532 · Lisle, Illinois20% of the homes
• ZIP Code 60440 · Bolingbrook, Illinois2.8% of the homes
• ZIP Code 60565 · Naperville, Illinois45 homes, under half a percent
• ZIP Code 60148 · Lombard, Illinois20 homes, under half a percent
• ZIP Code 60540 · Naperville, Illinois1 home, under half a percent

The areas it leads without holding most of the homes

Community High School District 99 is the largest district in 4 ZIP Code areas, and not one of them is wholly its own. Answer with its name alone and the answer misses 8,361 of the 48,944 homes those areas hold. That count is computed here from census blocks; the lookups that answer this question with a single name never print it.

Community High School District 99 is the largest name in ZIP Code 60559 · Westmont, Illinois and still holds a minority of it: 4,949 of 10,807 homes. The other 5,858 homes are with Westmont Community Unit School District 201 and Hinsdale Township High School District 86. This is the shape that makes a one-name answer worst — the name is right for fewer homes than it is wrong for.

Community High School District 99 holds 12,702 of the 13,657 homes in ZIP Code 60517 · Woodridge, Illinois, so its name is right for most of the area and wrong for the rest: 943 homes with Lemont Township High School District 210 and Naperville Community Unit District 203 and 12 homes in a district too small to name here.

In ZIP Code 60515 · Downers Grove, Illinois the split runs 11,618 to 928 and the larger part is Community High School District 99's: the rest is 884 homes with Lisle Community Unit School District 202 and Glenbard Township High School District 87 and 44 homes in a district too small to name here.

In ZIP Code 60561 · Darien, Illinois this district is one name among 8. Hinsdale Township High School District 86 leads with the largest share and Community High School District 99 holds 3,336 of the 9,798 homes counted there; no single name describes that area at all.

ZIP Code 60532 · Lisle, Illinois repeats the pattern with 4 names holding a real share: 2,690 of its 13,476 homes are Community High School District 99's, and the other 10,786 are not.

Community High School District 99 is not the name anyone would give for ZIP Code 60440 · Bolingbrook, Illinois — Valley View Community Unit School District 365U leads it — and Community High School District 99 holds 505 homes there all the same. Answer that area with one name and that is what it is wrong about.

The elementary districts that feed it

Students arrive at Community High School District 99 from 6 districts that run the lower grades on the same ground — Downers Grove Grade School District 58, which sends 40%, Woodridge School District 68, which sends 24% and Center Cass School District 66, which sends 7.1%. Each of those addresses therefore belongs to two districts at once, one for grade school and this one for high school, and neither name is the whole answer.

• Downers Grove Grade School District 5840% of Community High School District 99's homes come from here
• Woodridge School District 6824% of Community High School District 99's homes come from here
• Center Cass School District 667.1% of Community High School District 99's homes come from here
• Darien School District 616.3% of Community High School District 99's homes come from here
• Westmont Community Unit School District 2014.8% of Community High School District 99's homes come from here
• Lisle Community Unit School District 2024.5% of Community High School District 99's homes come from here

The names in this list are exact: the federal file gives the district of each band for every census block. The percentages are not. They spread each shared ZIP Code area's homes across the other band in proportion to the share each district holds there, because the file names the two districts of a block and not how a household moves between them. Read them as the size of the crossing, not as a count of houses.

Who it shares ZIP Codes with

Community High School District 99 shares ZIP Code areas with 21 different districts. The most frequent are Downers Grove Grade School District 58, Woodridge School District 68, Lemont-Bromberek Combined School District 113A and Center Cass School District 66. In a neighborhood this crowded the question is not which district serves the ZIP Code but which side of which street an address is on.

• Downers Grove Grade School District 585 shared ZIP areas
• Woodridge School District 684 shared ZIP areas
• Lemont-Bromberek Combined School District 113A3 shared ZIP areas
• Center Cass School District 663 shared ZIP areas
• Hinsdale Township High School District 863 shared ZIP areas
• Darien School District 613 shared ZIP areas

Where this district sits

• School districts in Illinois1,034 of 1,394 ZIP areas split
• Every district with a page here260 districts listed

What to do next

Ask the district office to confirm your street address. A district settles that question on its own site: look for a school locator, a find my school tool, or an attendance zone map. Where there is none, ask the office itself.

A ZIP Code is a set of mail delivery routes, not a boundary: in 8 of the 11 ZIP Code areas Community High School District 99 reaches, at least one other district holds a real share of the homes as well, and the line between them runs along streets. Only the district can say which side of that line an address is on.

This site links to no district website. None of the federal files it is built from publishes one, and a guessed address is worse than none. It is the district office, not a search engine, that settles an address.

If a house purchase depends on the answer, ask the district itself for written confirmation of that exact address. A listing is not a district record, and neither is this page.

What this cannot tell you

The homes were counted in the 2020 Census and the district lines are the 2026 boundary file. Nothing on this page adjusts one to the other. Where houses have been built or cleared since the count, a share here describes the place as it was counted rather than as it stands today, and in the fastest-growing ZIP Code areas that gap is the largest single source of error on this site.

A share on this page is a share of the homes in the ZIP Code area, not a probability for any particular address. Enrollment is decided by street address, and a district may run magnet, charter or choice programs that ignore the boundary entirely. If a decision depends on the answer, the district office is the only authority; this page shows what the federal boundary files say and when they were published.

A district boundary is not a school attendance zone. This site never says which school an address is assigned to: no current national dataset of attendance zones exists, and the district draws them itself. Nor is anything here endorsed or certified by the Census Bureau; we use their published files, and that is the whole of the relationship.

A ZIP Code is a set of mail delivery routes, not an area. What is mapped here is the Census Bureau's ZIP Code Tabulation Area, the closest published approximation to it. The two are not identical, and a handful of ZIP Codes used only for post office boxes or single buildings have no tabulation area at all.

Where these numbers come from

School district boundaries come from the Census Bureau's Census Geographic Relationship File, current 2026 vintage, which assigns every census block to a unified district or to an elementary and a secondary district. Homes and residents in each block come from the 2020 Census Redistricting Data (PL 94-171), H1_001 and P1_001. The ZIP Code areas come from the same Geographic Relationship File, block to ZIP Code Tabulation Area. District names and grade ranges come from the Census Gazetteer 2025, with 2020 for districts no longer listed.

The place name printed beside a ZIP Code comes from the Census 2020 ZIP Code Tabulation Area relationship files: place, county subdivision and county, taken 2026-09-06. It is a label rather than a measurement: the Census Bureau does not publish which post office a ZIP Code belongs to, so the place named is the one covering the most land inside the area, not the city the Postal Service prints on an envelope.

Everything else on this page — the shares, the counts of districts per ZIP, the comparison between the two grade bands, the rankings — is computed here from those files. The source publishes none of it. Snapshot taken 2026-09-03.