Blackwell was selected to design the Global War on Terrorism Memorial, which will sit adjacent to architect Maya Lin's Vietnam War Memorial and the in-progress Desert Shield and Desert Storm Memorial.
The process for the selection was unusual, as more than 150 architects and designers were contacted and asked to submit qualifications, but the shortlist and eventually the finalist, Blackwell, were chosen based on an interview process instead of visual designs.
"We had to convince them that we could tell a story here that would create opportunities to unite people, to honour, to empower to heal," Blackwell told Dezeen.
"To me, I don't think we're designing a thing, we're designing a place."
Blackwell, who has family ties to the military, said that the fact that the project was privately funded – via the The Global War on Terrorism Memorial Foundation – and the "non-partisan" nature of the institution encouraged him to put himself forward.
He wasn't able to give details on the design, but he said that there was definitely going to be a mix of the analogue and the digital.
An open-ended war memorial
According to the architect, both the site's relationship to the other memorials and the open-ended nature of the war on terror – an ongoing conflict with hard-to-define parameters – will impact the design.
"It's a unique memorial in the sense that it has a kind of a generally understood beginning – 9/11," said Blackwell.
"But it's an ongoing conflict. So most all of the memorials on the mall have distinct beginnings and this doesn't."
Blackwell added that the design will take into account both civilians and members of the armed forces and the families of those involved in ongoing conflicts associated with the war.
"We need things we can unite around that are fundamental to who we are as a country," he said. "But war is difficult. It's a mess."
While no designs have been released, Blackwell explained that he will visit DC soon to see the site and start planning with his team.
The war on terror is a term used to denote the military actions launched by the United States and its allies against state and non-state actors in several nations, specifically in the Middle East.
The term has since fallen out of usage, with US governmental departments distancing themselves from the term as early as 2009.
Other monuments underway in the United States include a Holocaust memorial in Florida designed by LA studio Brooks + Scarpa.
The main photo is by Carol M Highsmith.