As Jacoby Ellsbury leaves the Red Sox for the Yankees and a seven-year, $153 million contract, the outfielder is celebrated as the Ellsbury Dough Boy by the New York Daily News and denounced as a defector by Boston fans, and all the tedious bickering between the two cities is yet another reminder that Boston and New York really ought to get a room.

Because the secret truth is, Boston and New York love each other. They need each other. And beyond minuscule distinctions, they are each other. Boston and New York could be fraternal twins, one named Teddy Ballgame, the other Donnie Baseball. No sleep till Brookline. Or is it Brooklyn?

Their respective rivers, the Charles and the Hudson, have been confluent since the late 1980s, when Charles Hudson pitched for the Yankees, who owe a greater debt to Boston than they will ever acknowledge. Of course, like the ubiquitous buses that ply their routes every half hour between Chinatown (the one in New York) and Chinatown (the one in Boston), these things go both ways.

Boston gave New York Babe Ruth, but also Patrick Ewing, Michael Bloomberg and Sen. Robert F. Kennedy, and it gave the world the first telephone. New York gave Boston Manny Ramirez and the world the first sports bar. So you can be grateful to both cities next time you're in a sports bar and the telephone rings, and the bartender answers and looks you in the eye and says, "He's not here."

Phil Esposito played hockey in Boston for eight seasons and New York for six. Before he coached the Patriots, Bill Belichick was a Giant and—very briefly—a Jet. After he coached the Giants—and before he coached the Jets—Bill Parcells was a Patriot. If the Pats and the Jets (and Bruins and Rangers) hate each other, that hatred is a form of self-loathing.

As Parcells can attest, Bostonians pronounce Tuna as Tuner, and vice versa. Most Americans think of Boston and New York—when they think of them at all—as a pick-your-poison choice of cartoon accents: pahk the cah vs. fuhgeddaboutit.

And while Ellsbury makes the subtle shift from "wicked pissah" to "howyadoin'," it's worth remembering that countless other Red Sox later played for the Yankees, and not all of them left for more money, though that is the ancient narrative about the two cities: New York the capital of high finance, Boston the capital of higher education. "In Boston they ask, how much does he know?" Mark Twain wrote the century before last. "In New York, how much is he worth?"

As a result, Boston inspires elegant sports headlines (HUB FANS BID KID ADIEU, above John Updike's New Yorker story on Ted Williams) while New York headlines cry out nakedly for newsstand sales (SPANK HIM, YANKS, beside a Post picture of Pedro Martinez in a diaper).

Martinez pitched for the Red Sox but also the Mets, to whose games he commuted from his home in Connecticut. Those of us who reside in that small state between New York and Massachusetts often feel like children who can hear their parents fighting. Some are literally caught in the middle—exactly midway between New York and Boston—living on the invisible border that separates Yankees and Red Sox fans, the Munson-Nixon Line.

That line is razor-thin. One city is the self-styled center of the world, while the other is the self-anointed Hub of the Universe. The two cities have inspired the world with their response to terror attacks. And together, they've acted as a twin-blade razor to remove murderer Whitey Bulger from our midst—Boston convicting him, Brooklyn imprisoning him.

All of which is to suggest that Boston and New York share the same "special relationship" as the U.S. and Great Britain, countries now divided only by a common language. Except the cities are divided by nothing.

Or nearly nothing. My SI colleague Stephen Cannella was raised in Connecticut, educated in Boston and works in New York, and he suggests there really is an unmendable fault line between the two cities: chowder. "New England's is made of clams, cream and the tears of angels," he says, "while Manhattan's is an abomination."

And so they'll fight on, two cities divided by soup.

The secret truth is that Boston and New York love each other. They need each other. They are each other.

Which two U.S. cities have the best rivalry?

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PHOTODAMIAN STROHMEYER/SPORTS ILLUSTRATED ILLUSTRATION

HOLE YARDS PAR R1 R2 R3 R4
OUT
HOLE YARDS PAR R1 R2 R3 R4
IN
Eagle (-2)
Birdie (-1)
Bogey (+1)
Double Bogey (+2)