What the Costco Coming to Southborough Actually Means for Your Home's Value

What the Costco Coming to Southborough Actually Means for Your Home's Value

Quick Answer: Costco cleared the final zoning board hurdle in July 2026 for a 17.81-acre site at 21 Coslin Drive in Southborough, off Route 9 near I-495. Local officials expect it to open by summer 2027. For homeowners in Southborough and neighboring MetroWest towns, this is one of the biggest commercial developments in decades and will affect Route 9 traffic, commercial tax base, and long-term property values. Here's what buyers, sellers, and current owners should actually know.

If you live in Southborough or shop through the Route 9 corridor, you've probably heard the Costco news by now. On July 15, the Zoning Board of Appeals voted to grant Costco variances for the retaining walls and light pole heights it needs to build. That's a big signal. It moves the project from "possibility" into "planning."

I want to talk about what that actually means if you own a home here, or you're thinking about buying or selling in Southborough or the surrounding MetroWest towns.

Where is the Costco going?

The site is 21 Coslin Drive, a 17.81-acre parcel adjacent to Route 9, near the Southborough-Westborough line, and just feet from I-495. Framingham-based Atlantic Management Corp. closed on the property at the end of January for approximately $6.9 million, according to public deed records.

It's the same site where EMC once had a major campus. That building came down, and it has sat vacant for years while the town figured out what to do with it. Now, it's slated to become the first full Costco in Central Massachusetts in decades.

When will it open?

Local officials are targeting summer 2027. That's not guaranteed. There are still permitting steps ahead — the Planning Board site plan review and traffic study haven't been submitted yet. But with the AG's zoning approval done and the ZBA variances granted, the biggest legal hurdles are behind them.

Why the town wanted this

Southborough's commercial tax base has been shrinking. Pre-COVID, the town was 80% residential and 20% commercial for tax purposes. Today that has shifted to roughly 84% residential and 16% commercial, and homeowners have been carrying more of the load.

Town Meeting approved the zoning change 771 to 12 last fall. That is not a close vote. Residents were signaling they wanted the commercial tax base to grow so residential taxes don't have to.

Costco would help.

What it likely means for your home value

Here is where I have to be careful and honest.

In the short term (before opening, 2026 to summer 2027): probably minimal impact. Buyers already know the project is coming. Sellers are not seeing a "Costco premium" yet.

In the medium term (open and operating, 2027 to 2029): expect a mixed effect. Traffic on Route 9 will increase. That will be a drawback for homes closest to that corridor. But the commercial tax base will strengthen, which typically holds residential taxes steadier. Southborough already has strong school-district reputation and quick MetroWest highway access. Costco adds convenience.

In the long term (2028 and beyond): the tax base benefit compounds. Southborough becomes a slightly more commercially-anchored town, less reliant on residential taxes, and more of a regional destination. Homes here should benefit from that stability.

Who's most affected

If you live within a half mile of the Coslin Drive corridor, you'll experience the traffic impact directly. If you live in a neighborhood closer to downtown Southborough, the Common, or the school corridors, you're farther from the impact but still benefit from the tax base story.

If you own a home in Westborough right on the Southborough line, you actually get most of the same benefit (Costco convenience, tax base indirectly stabilizing regional home values) without living in the town paying the traffic price.

What buyers and sellers should think about right now

If you are thinking about selling in the next 12 months: the market is not "priced in" to Costco yet. Sell on your home's own merits. Do not wait for the Costco boost that may not materialize.

If you are thinking about buying in Southborough now: you are buying before a major amenity opens. That's generally a fine time to buy in a stable town. Just factor Route 9 traffic reality into your commute planning if you're near the Coslin corridor.

If you already own and are just wondering: this is good news for your long-term tax picture and slightly mixed for your immediate quality of life, depending on where in town you are.

What I'm watching next

Three things I'll be tracking as this progresses:

1. Traffic study— this comes with the site plan application. It will tell us exactly how much additional Route 9 traffic to expect.
2. The alcohol license vote— Costco still needs an approved retail alcohol license from the Select Board. That was petitioned for this spring.
3. Site plan approvals— this is where actual construction timing gets nailed down.

Frequently Asked Questions

Will Costco lower my Southborough property taxes?

Not directly, and not immediately. What it will do is strengthen the commercial tax base so residential taxes don't have to grow as fast. Over 10 years, that's meaningful. Over 1 year, marginal.

Will Costco hurt my property value if I live near Route 9?

Homes closest to the Route 9 corridor (within about a half mile of Coslin Drive) may see slightly increased traffic burden. Homes farther in town benefit from tax base stability without the traffic price. Historical data on similar Costco openings shows most homes see stable or slightly positive value over 3-5 years.

Should I sell before Costco opens?

Only if you were going to sell anyway. There is no evidence of a "sell before Costco" premium developing. Sell when the life reason matches, not when the retail schedule does.

What if I own commercial property in Southborough?

You are the biggest winner in this. Costco brings foot traffic and regional interest that tends to lift adjacent commercial values.

Is Costco going to be open by summer 2027?

Officials are targeting that. Not guaranteed. Site plan, traffic study, and alcohol license all still need approval.