The 270 South to 70 West Interchange in St. Louis County is Labeled Wrong
I’ve lived in the St. Louis area my whole life. I have a pretty good handle on the interstates, which are smooth and clear in some places and annoying in others.
Interstate 270 is … well, it’s fine. It was constructed in the 1960s, in the time of the post-World War II suburb and vehicle boom — and it’s been enlarged and updated over the years — so it’s one of the more navigable arteries in the St. Louis area. That’s important, because 270 is crucial to travel throughout St. Louis County and parts of Illinois.
I have my pet peeves about 270, but one stands out. It’s an annoyance for locals but one that might be a larger problem for drivers not from around here.
One of the I-270 South interchanges, at I-70, is mislabeled, and has been for years.
On Interstate 270 South just past 370, drivers encounter a pair of exit signs, one for interstate 70 and one for another exit, St. Charles Rock Road (MO-180).
As you can see in the picture, there are five lanes at this point on 270. The three left lanes are through lanes that continue past the interchange. The fourth from the left lane is an exit only lane for Interstate 70, while the fifth from the left — the far right lane at this point on the road — is an exit only lane for St. Charles Rock Road (MO-180).
A second sign farther south reinforces this lane arrangement.
Again, the second sign points to the fourth from the left being the exit only 70 lane, while the fifth from the left (or far right) is the exit only St. Charles Rock Road (MO-180) lane.
But before you even get past the second sign, there’s also a sign — both figuratively and literally — that something isn’t quite right.
Because right after the second sign, the fifth lane from the left — the far right — splits into two. One of those two new lanes is St. Charles Rock Road. The other … is I-70 West.
That’s not at all what the previous signs indicated. The previous signs indicated that the fourth from the left would be splitting into 70 West and 70 East. Instead, the fifth from the left (far right) splits into 70 West and St. Charles Rock Road.
In other words, if you were in that fourth lane from the left, thinking you were headed to 70 West, you’re suddenly realizing you are in the wrong lane, and you have to get over one lane to the right in order to end up in the right place.
Does this matter? For locals, it’s no big deal — they’ll know what lane to be in.
It’s also not a huge deal on a day when traffic is light.
But I think about out-of-state traffic, to say nothing of semis new to the area, who get caught in rush hour who suddenly are in the wrong lane because the signs are wrong.
Road signs have one job, which is to help drivers know where to go. Two signs on 270 South fail at that.
I’ve reached out to the Missouri Department of Transportation twice about this interchange: once in 2021 and once in 2023. Both times I heard back from a MoDOT rep saying they’d look into it.
As of 2025, nothing has changed.
