Last Monday, New Haven sold two downtown streets to Yale University for $3 million. Although the Board of Aldermen approved it handily — the vote was 21-8 —public reaction was more mixed.

Protesters were forcibly removed from city hall during the vote. One alderman reportedly said that selling public access would be non-negotiable, and many Internet commenters wondered whether selling streets was legal. But New Haven has a long tradition of exchanges of streets between the city and private owners — indeed, there was a vibrant market for streets in the city's earliest days. That history may show why the university's purchase of the streets is the best thing for the city and for Yale.

In 1727, Connecticut passed "An Act for Enabling the Proprietors … to Make Exchanges of said Common Land, for the Procuring Needful Convenient Highways." The act allowed towns to exchange common land — be it a larger parcel or an existing street — for a private owner's land, which the town would then convert into a street. This was powerful legislation, and it was responsible for much of the development of early Connecticut towns.

Although New Haven started out with a centrally planned nucleus of streets (the nine squares), the rest of the city formed piecemeal, with residents granting land back to the city for streets or else petitioning for streets they thought would be useful. The city needed the flexibility to pawn off pieces of streets that proved less important or successful than they had hoped.

Records show New Haven exchanging these kinds of streets to build a stockpile of better land, which it could then use for streets or sell to raise funds for future development. In 1769, the proprietors of New Haven directed the town selectmen — forerunners to today's aldermen — to "find waste Land or needless highways to Dispose of" in order to obtain new roads and infrastructure. And they did: In this period, the town frequently traded strips of old highways to obtain new highways and more favorable pieces of land.

It would go something like this: The town would contact a landowner, offer a trade and start to put together a better highway. This process cobbled together what became New Haven's Union, Fair, Water and Olive streets as we know them near Wooster Square — and it also explains why those streets are a bit less straight than the pre-planned State Street, just to the west.

What are the advantages of allowing a city to dispose of streets that have become less valuable to it and more valuable to private owners? Well, for one, the streets become subject to a sort of Darwinian selection: Good roads survive, and less useful roads can be sold or exchanged to the highest and most interested bidder.

Back in the 18th century, as with Yale now, that was usually the landowner neighboring the old street. Should you find yourself in the New Haven land records vault at city hall, open volume 15 to page 422, and you'll find a record from 1751 of Joseph Basset giving the city a piece of land in order to obtain an old, worthless partial highway near land he stood to inherit from his father. It was a win-win: The city was able to build new, more useful infrastructure, and Basset got a strip of land that he could make better use of than the city could.

Although Yale purchased the streets, rather than exchanging land, the same idea may apply today. Yale has leased the streets for 23 years, it likely values the streets more than the city, it will undoubtedly improve the university's infrastructure, and Yale may be in the best position to make Wall and High streets better for all New Haven pedestrians, bicycle traffic and other transit. Meanwhile, the city gets a large sum to use however it wishes. Time will tell whether this claim holds true. In the meantime, New Haven's citizens should know that there is a long history of streets cycling into and out of the public domain as the city's and residents' needs change. But good luck bidding on I-91 — that's probably not for sale yet.

Molly Boyle of Boston graduated from Yale Law School in 2011.