The smallest town on the Vineyard may soon get a tiny bit smaller.

Chilmark and Aquinnah which share a town boundary line are considering changing the line for the first time in more than 150 years — by about 200 square feet.

A joint meeting of selectmen from the two towns this week explored the idea of changing the lot line along Menemsha Creek on Boathouse Road.

The proposal comes after years of confusion over three lots that the cross town lines. The lots are leased by both towns to commercial fishermen. Two of the lots which have fishing shacks on them are in the peculiar situation of hugging both town lines. Now under discussion is a plan to adjust the lines so one building is completely located in Chilmark and the other is in Aquinnah.

The changes would require voter approval at town meetings in both towns. If the changes clear that hurdle they will next go to the state highway department for approval. And finally, the state legislature must sign off on the change.

Chilmark selectman Warren Doty said engineering drawings show Aquinnah would lose about 200 square feet with the change.

“The point is to get the two buildings in question in either town and not through a town line that goes through somebody’s lot,” he said.

“I know it’s a complicated process,” Chilmark selectman Bill Rossi said. “But it would be simpler for each town . . . if it took a couple of years to correct I think we could all stand that to get it cleaned up.”

Chilmark town documents show that the current town line was established between the towns of Chilmark and Gay Head in 1855. The northerly end of the boundary split Menemsha Creek in two — half for Chilmark and half for Gay Head — and followed a sharp westerly turn toward what is today Lobsterville Beach.

In 1906, a new channel was dredged and Menemsha basin was created for the harbor. The dredged material was used to create a jetty for the fishermen’s buildings. A new granite post four feet high marked the town line by the old post office in Menemsha when work was complete. One side said “C” and the other “GH”.

With a new dredged channel, stone jetty and heavy tidal currents, the path of Menemsha Creek has changed drastically over the years. But the town line remained the same.

“We’re not losing anything in doing this, you’re accommodating Chilmark and we’re gaining beause it gives us more control over our property,” said Aquinnah selectman Jim Newman.

But his colleague Spencer Booker was hesitant.

“We’re the second smallest town in the commonwealth of Massachusetts and you want to make it smaller,” he chided.

The title of second smallest town in the state has been folklore for years, but it refers to population, not land mass. With a total land mass of 5.4 square miles, Aquinnah is actually the 18th smallest town in the commonwealth. Chilmark has a total land mass of 19.1 square miles. Nahant in Essex County takes the prize for smallest when it comes to land mass, with 1.2 square miles.

The lot line problem has caused a muddle when it comes to assessments. The town line splits the shack formerly owned by Alfred Vanderhoop and a shack belonging to Jonathan Mayhew. Aquinnah taxes the Vanderhoop shack just under $50 and the Mayhew shack about $100. A longstanding gentlemen’s agreement over property tax domains has sufficed rather than parcelling out which square footage belongs to which town, Mr. Booker said.

“Up until now it’s been the assessors and the town of Chilmark have assessed a lot and the assessors in the town of Aquinnah have assessed a lot,” he said.

Chilmark has never assessed the Vanderhoop shack, Mr. Doty said.

“We’d be happy to not assess that property and leave it up to the town of Aquinnah,” he said. “It has to feel like a good deal for both sides.”

Selectmen took the plan under advisement. It will be posted on the Aquinnah town website for public review.