On June 5, 1943, aged 23, Gillespie moved to New York City. There she took a job at the B. Altman department store as assistant art director. She also joined the Art Students League where she was exposed to new ideas about techniques, materials, and marketing. She also created works at Atelier 17 printmaking studio, where Stanley William Hayter encouraged to experiment with her own ideas.
She and her husband, Bernard Israel, opened a restaurant and night club in Greenwich Village to support their family. She returned to making art in 1957, and worked at art full-time after they sold the nightclub in the 1970.
Gillespie also maintained a studio in Florida and served on the Board of Trustees of the Maitland Art Center in Maitland, Florida (1996-1999) and on the Broward County Cultural Affairs Council (1993-1994).
By the 1980s, Gillespie's work had come to be known internationally. She completed many commissions for sculptures in public places, including the Lincoln Center and Epcot Center in Orlando, Florida.
Her work is unique in its use of ribbon-like shape and use of bright colors. Her sculptures are crafted out of aluminum covered in enamel. Her “Colorfall,” is a 40-foot tall sculpture hanging in the lobby of Wilmington's Thalian Hall Center for the Performing Arts.Wikipedia