The width of Central Park may be only three city blocks long, but the gulf between the Upper West Side and the Upper East Side first widened as soon as the two disparate neighborhoods became populated in the years following the opening of the park.

Upper West Side

The Upper West Side, which is anything west of Central Park and north of Fifty-ninth Street, has always attracted more bohemian residents. Intellectuals, artists, and others in creative fields settled there in increasing numbers after World War I.

By the turn of the century, many Russian Jewish immigrants, who originally settled on the Lower East Side, began looking for living quarters uptown as their businesses prospered. But new money in general — and Jews in particular — were not made welcome on the Upper East Side. Seeing an opportunity, some of the earliest apartment buildings on the Upper West Side were built by developers specifically looking to attract Jewish tenants.

Upper East Side

Up until construction began on the Metropolitan Museum, the Upper East Side was mostly pastureland. But the cachet of the museum prompted some big money names to buy land nearby to build houses. Stanford White designed a house for Charles Tiffany a block east of the Park. But the person who “made” the Upper East Side was society maven Caroline Astor who commissioned a château to be built at Sixty-fifth and Fifth.

Over the next decade, dozens of high society families built homes along Fifth Avenue, earning it the nickname Millionaire's Row. Not long after, private clubs such as the Metropolitan and the Knickerbocker opened in the area to accommodate the local residents. Once the train tracks were removed and the street paved, Fourth Avenue was renamed Park Avenue. Along with Fifth and Madison Avenues, these streets east of the park became New York's most sought after addresses by the status conscious.

The East Siders were very class conscious and regarded artists and intellectuals as inferior, albeit occasionally fascinating. They viewed the nouveau riche with tacit disdain. Although Upper East Side residents considered themselves the social trendsetters in the pre-World War II era, they eventually took a cue from the West Side. By the early 1940s, most of the extravagant single-family manses along Fifth Avenue gave way to million-dollar apartments.