A "school", or aesthetic, of electronic music that arose in the New York City area in the mid-1960s. Musically, the East Coast school had its roots in the classical music and bebop jazz scenes in the New York area at the time. However, it was also influenced substantially by a decision of convenience that Bob Moog made when he designed his first modular synthesizers in 1965: needing to decide on how the performer would control the instrument, he realized that a conventional music keyboard activating electrical switches, a la the electronic organs of the time, would be inexpensive and would be something that would be a familiar element to performers encountering a synth for the first time.
This encouraged classical and jazz musicians in the area to take up the Moog instruments and add it to the music that they already knew and were performing. Moog worked at making sure that his instruments supported this. When Wendy Carlos was assembling Switched-on Bach, Carlos and Moog worked on a number of improvements to the Moog modular synths, and Moog also took suggestions from musicians such as jazz player Sun Ra and (a bit later) progressive rock player Keith Emerson. The now-traditional subtractive synthesis chain of VCO-VCF-VCA chain and its refinements grew out of this, as well as keyboard performance features such as velocity and aftertouch sensitive keyboards, and the pitch wheel.
The advent and success of the Minimoog, which was specifically built around this chain, firmly established it as the dominant aesthetic for synthesizers in popular music through the 1970s -- somewhat to the disappointment of many of the people involved. A huge number of synths inspired by, or imitating, the Minimoog appeared; some of these were very good in their own right and had their own innovations, but many were merely "me too" products. Performers of other aesthetics came to regard the East Coast school as lacking in innovation. However, it was the East Coast design techniques that were able to develop affordable polyphonic synths in the early 1980s, without which New Wave music would not have happened.
East Coast went into decline in the late '80s, with the decline in popularity of progressive rock and fusion jazz -- two styles that had relied on the East Coast aesthetic as a significant part of their sound -- and the advent of digital synthesizers and samplers, which sought to break away from the sameness and the limitations of East Coast subtractive synthesis. However, the sampler era of the '90s quickly produced its own new set of "me too" and limited products, and performers began to develop a new appreciation for the East Coast aesthetic. The modular synthesizer revival that began in the late '90s helped significantly by taking East Coast back to its first principles, and getting the school out of some of the stylistic and design traps that it had been locked into. With the advantage of three decade of technology development since Bob Moog designed his first modulars, the new modular designers were able to offer capabilities that would have been unaffordable (or even impossible) in Moog's day. Simultaneously, the advent of the virtual analog synths brought the East Coast techniques down to a low price point and introduced it to a new generation of young performers, who now had access to subtractive synthesis without the expense and headaches of dealing with the now-vintage analog synths of the '70s.
Today, the East Coast school is in the best shape it has been in since the 1960s. A large enough variety of products, both vintage and new, are available that no performer ever needs to be locked into a specific sound. The emphasis is still on instruments designed for melody, harmony, and performance, but the instruments are flexible enough to be used for a wide variety of styles. Instruments are still based mostly on the subtractive synthesis chain, but the new synths have been able to accommodate a variety of synthesis methods and techniques, using mixes of analog and digital circuitry. And even the traditional subtractive synthesis elements have more capability than before: VCOs offter more waveforms (and digital wavetable oscillators can offer a huge variety); VCFs have more modes and options, and VCAs are more accurate and more able to accommodate uses other than just basic envelope control. A source of disappointment is that the East Coast school has never achieved the impact on classical music that it hoped for (few of the performers who attempted traditional classical pieces with synths ever did it as well as Carlos did, and Carlos herself is no longer active). And the analog polysynths have disappeared, due to the integrated circuits that they relied on being no longer available.