[6] The Upper East Side is part of Manhattan Community District 8, and its primary ZIP Codes are 10021, 10028, 10065, 10075, and 10128.

[18] Before the arrival of Europeans, the mouths of streams[19] that eroded gullies in the East River bluffs are conjectured to have been the sites of fishing camps used by the Lenape, whose controlled burns once a generation or so kept the dense canopy of oak–hickory forest open at ground level.

[20] In the 19th century[a] the farmland and market garden district of what was to be the Upper East Side was still traversed by the Boston Post Road and, from 1837, the New York and Harlem Railroad, which brought straggling commercial development around its one station in the neighborhood, at 86th Street, which became the heart of German Yorkville.

The area was defined by the attractions of the bluff overlooking the East River, which ran without interruption from James William Beekman's "Mount Pleasant", north of the marshy squalor of Turtle Bay, to Gracie Mansion, north of which the land sloped steeply to the wetlands that separated this area from the suburban village of Harlem.

[23] By the mid-19th century the farmland had largely been subdivided, with the exception of the 150 acres (61 ha) of Jones's Wood, stretching from 66th to 76th Streets and from the Old Post Road (Third Avenue) to the river[25] and the farmland inherited by James Lenox, who divided it into blocks of houselots in the 1870s,[26] built his Lenox Library on a Fifth Avenue lot at the farm's south-west corner,[27] and donated a full square block for the Presbyterian Hospital, between 70th and 71st Streets, and Madison and Park Avenues.

[23] The fashionable future of the narrow strip between Central Park and the railroad cut was established at the outset by the nature of its entrance, in the southwest corner, north of the Vanderbilt family's favored stretch of Fifth Avenue from 50th to 59th Streets.

[29] A row of handsome townhouses was built on speculation by Mary Mason Jones, who owned the entire block bounded by 57th and 58th Streets and Fifth and Madison.

In 1870 she occupied the prominent corner house at 57th and Fifth, though not in the isolation described by her niece, Edith Wharton, whose picture has been uncritically accepted as history, as Christopher Gray has pointed out:[30] It was her habit to sit in a window of her sitting room on the ground floor, as if watching calmly for life and fashion to flow northward to her solitary door... She was sure that presently the quarries, the wooden greenhouses in ragged gardens, the rocks from which goats surveyed the scene, would vanish before the advance of residences as stately as her own.

[32] Most members of New York's upper-class families have made residences on the Upper East Side, including the oil-rich Rockefellers,[33] political Roosevelts, political dynastic Kennedys,[34] thoroughbred racing moneyed Whitneys,[35][36] and tobacco and electric power fortuned Dukes.

[37] Construction of the Third Avenue El, opened from 1878 in sections, followed by the Second Avenue El, opened in 1879, linked the Upper East Side's middle class and skilled artisans closely to the heart of the city, and confirmed the modest nature of the area to their east.

The unbuilt "Hamilton Square",[38] which had appeared as one of the few genteel interruptions of the grid plan on city maps since the Commissioners' Plan of 1811, was intended to straddle what had now become the Harlem Railroad right-of-way between 66th and 69th Streets; it never materialized, though during the Panic of 1857 its unleveled ground was the scene of an open-air mass meeting called in July to agitate for the secession of the city and its neighboring counties from New York State, and the city divided its acreage into house lots and sold them.

[40] Gracie Mansion, the last remaining suburban villa overlooking the East River at Carl Schurz Park, became the home of New York's mayor in 1942.

[42] Demolishing the elevated railways on Third and Second Avenues opened these tenement-lined streets to the construction of high-rise apartment blocks starting in the 1950s.

[46][47][48] This brought in new local business to the area and had positive impact on real estate prices in the Upper East Side.

[54]: 7 As of the 2000 census, twenty-one percent of the population was foreign born; of this, 45.6% came from Europe, 29.5% from Asia, 16.2% from Latin America and 8.7% from other areas.

[59] Traditionally, the Upper East Side has been dominated by wealthy White Anglo-Saxon Protestant families.

[60][61][62] Given its very high population density and per capita income ($85,081 in 2000), the neighborhood contains the greatest concentration of individual wealth in Manhattan.

[2] The Upper East Side maintains the highest pricing per square foot in the United States.

[65] Politically, the Upper East Side is in New York's 12th congressional district, which has a Cook PVI of D+34[66] and is currently represented by Democrat Jerry Nadler.

[75] The Upper East Side is notable as a significant location of political fundraising in the United States.

The top ZIP Code, 10021, is on the Upper East Side and generated the most money for the 2004 presidential campaigns of both George W. Bush and John Kerry.

[89] The Upper East Side is served by multiple New York City Fire Department (FDNY) fire stations:[92] As of 2018[update], preterm births and births to teenage mothers in the Upper East Side are lower than the city average.

[54]: 14 The concentration of fine particulate matter, the deadliest type of air pollutant, in the Upper East Side is 0.0083 milligrams per cubic metre (8.3×10−9 oz/cu ft), more than the city average.

[54]: 6  The percentage of the Upper East Side students excelling in math rose from 61% in 2000 to 80% in 2011, and reading achievement increased from 66% to 68% during the same time period.

[103] The Upper East Side's rate of elementary school student absenteeism is lower than the rest of New York City.

[55]: 24 (PDF p. 55) [54]: 6  Additionally, 91% of high school students in the Upper East Side graduate on time, more than the citywide average of 75%.