Final answer:
Frank Lloyd Wright's concept of organic architecture has been pivotal in the development of American Architecture, alongside the Chicago School and later Postmodernism by architects like Philip Johnson and Frank Gehry. Additionally, the Art Deco movement and Sullivan's 'form follows function' have been influential.
Step-by-step explanation:
Significant Figures in American Architecture
The quest to define an American Architecture has been influenced by a number of significant architects. Frank Lloyd Wright is a towering figure in this regard, with a career that spanned over 70 years, designing more than 1,000 structures with the intention that they be in harmony with humanity and their environment. This philosophy is known as organic architecture. Wright's influences included Louis Sullivan, Japanese architecture, the English Arts and Crafts movement, and notably, nature, which informed his prairie house designs.
Other important architects associated with the Chicago School, such as Dankmar Adler, Henry Hobson Richardson, Daniel Burnham, and Louis Sullivan, influenced the direction of American architecture. They, along with figures such as Philip Johnson and Frank Gehry in the later years, contributed to the evolving Postmodernism in architecture which has left a significant mark on American cities.
In the early 20th century, Art Deco and Streamline Moderne emerged as key architectural styles, shaping the aesthetic of American urban landscapes. The architectural ethos of the time, encapsulated by Louis Sullivan's principle that 'form follows function,' also played a critical role in the evolution of the nation's architectural identity.