Projects by Blackwell's eponymous Arkansas firm in the southern state include a pediatric clinic with a vivid red facade, the addition of a design centre to the University of Arkansas and an orthodox church.
"The Gold Medal honours an individual whose significant body of work has had a lasting influence on the theory and practice of architecture," said the AIA.
"Blackwell is being recognised for his important body of transcendent work in the hills of Northwest Arkansas."
Marlon Blackwell Architects has completed a number of other cultural and public projects like a Montessori Elementary school and a high school – both of which are also in Arkansas – as well as a visitor's pavilion at the Indianapolis Museum of Art in Indiana, and the renovation of a vast park in Tennessee.
The firm also developed a series of affordable prototype houses for families that lost homes in Hurricane Katrina.
Blackwell's work was praised by Canadian architect Brian MacKay-Lyons, who supported the decision to bestow him with the 2020 AIA Gold Medal.
"Marlon Blackwell is a student of his 'place' in the world," said MacKay-Lyons in his letter supporting Blackwell's nomination.
"His is a uniquely American architecture; he builds confidently upon the American cultural landscape," MacKay-Lyons added. "His 'cultural realist' approach is democratic, looking to the ordinary and the everyday for inspiration. It is connected to society, rather than being aloof. This is not a nostalgic architecture, but an architecture of its time and place."
Blackwell was born in Fürstenfeldbruck, Germany in 1956, and spent his childhood living in various places, including the Philippines, Florida, Colorado, and Alabama, where he earned his Bachelor's degree in architecture from Auburn University.
He gained a master's degree from New York's Syracuse University, while studying abroad in Florence, Italy. He then moved to Arkansas, where he eventually established his eponymous studio in 2000.
In addition to his architectural practice, Blackwell has been a professor of architecture at the University of Arkansas since 1992. During his time at the school, he established the University of Arkansas Mexico Summer Urban Studio at the Casa Luis Barragán in Mexico City.
"As a practicing architect and educator myself, I have become aware of the growing estrangement between the world of practitioner and that of the academy," said American architect Thom Mayne, who was awarded the 2013 AIA Gold Medal.
"Marlon teaches, as do I, because of the great sense of responsibility to add a measure of reality to the education of architectural students while also supporting the theoretical or less pragmatic aspects of their education."
Blackwell is the 76th recipient of the AIA Gold Medal, which is awarded annually to architects in recognition of their legacy to the field. The institution has bestowed a number of well-known names with the honour like Frank Lloyd Wright, Louis Sullivan, Le Corbusier, Louis I Kahn, IM Pei and Moshe Safdie.
This year's winner was Richard Rogers, the 2018 winner was James Polshek, while 2017 award was given to Paul Revere Williams, who became the first black architect to receive the medal. In 2016, the winners were husband-and-wife team Denise Scott Brown and the late Robert Venturi.
Marlon Blackwell's portrait is by Mark Jackson.