The Regional Plan Association is an independent, not-for-profit regional planning organization, founded in 1922, that focuses on recommendations to improve the quality of life and economic competitiveness of a 31-county New York–New Jersey–Connecticut region in the New York metropolitan area. Headquartered in New York City, it has offices in Princeton, New Jersey, and Stamford, Connecticut.

In 1922, the Russell Sage Foundation appointed the Committee on the Plan of New York and its Environs with the goal of creating a comprehensive development plan with to enhance quality of life for residents. The first Committee meeting was held on May 10, 1922, including prominent attendees such as Herbert Hoover, Charles Dyer Norton, Elihu Root, Lillian Wald, Charles Dana Gibson, and Eleanor Robson Belmont. Between 1927 and 1929, a series of ten technical volumes on manufacturing, transportation, and community planning was published as precursors to the first Regional Plan. In 1929, the RPA was formally incorporated. That same year, the first Regional Plan was published, the first regional plan in the United States.

In 1930, George McAneny became RPA's first president. The first plan included ambitious proposals such as building a new city upon the New Jersey Meadowlands that would fit five million people at the cost of $125 million. In 1931, Volume II of the First Plan was introduced, which focused on urban design. This plan included plans such as demolishing blighted areas on the Lower East Side.

Expansion of public parks was another important factor in the first plan, as it identified several natural areas to be acquired for public use. This included the establishment and expansion of sites including Garret Mountain Reservation in Paterson, NJ, Great Kills Park on Staten Island, and the Palisades Interstate Park System.

In the late 1930s, the RPA successfully prevented Robert Moses's proposal to build a bridge between Battery Park and Brooklyn, resulting in the Brooklyn-Battery Tunnel being built instead. Throughout the 1930s and 1940s, the region's highway and parkway network largely followed the RPA's plan, including projects such as the George Washington Bridge, the Belt Parkway, the Henry Hudson Parkway, and East River Drive (now FDR Drive). Since the 1930s, the RPA recommended a highway between the Triborough Bridge and Gowanus Parkway, which later became the Brooklyn-Queens Expressway when it was completed in 1964.

In 1942, a study was conducted by the RPA about traffic and parking in Manhattan below 61st Street, where they planned to build parking structures near transit, as well as advocating for a form of congestion pricing.

During World War II, the RPA worked to address housing, transportation, and civilian protection efforts, particularly due to the convergence of workers in defense industries. Following World War II, population growth exploded in the suburbs, as opposed to New York City and other urban areas as it had been decades prior. The suburban population doubled, and the newly built road network encouraged sprawl. The RPA advocated for the development of land near to transit and to Manhattan. RPA advocated for comprehensive community planning, improved building codes, and large-scale development of regional city centers. In 1947, the RPA released a report called Airports of Tomorrow, which called for improvements to the region's airport system.

In the late 1940s, the RPA advocated for the "neighborhood unit", which promoted design principles for neighborhoods, including garden apartments, walkable shopping centers, and minimal through-traffic. These ideas were implemented in places such as Fresh Meadows and Forest Hill Gardens in Queens, and Radburn, New Jersey.