FDR created the WPA through executive order in his first 100 days in office. The Works Progress Administration (WPA) was created by Executive Order #7034 on May 6, 1935. He had the authority for this Executive Order via the Emergency Relief Appropriation Act of 1935. Jacob Lawrence worked for the WPA –
I watched two documentaries that were both significant in making the connections between Diego Rivera and the WPA. The first was the PBS documentary “The Life and times of Frida Kahlo” by Amy Stechler followed by “Enough to Live on, The Arts of the WPA” a film by Michael Maglaras.
Rivera painted 27 murals between 1932 and 1933.
Here is an image from the Coit tower in San Francisco.
More detail to follow.
http://socialwelfare.library.vcu.edu/eras/great-depression/wpa-the-works-progress-administration/