Though it's certainly had its scandals, the U.S. Secret Service still carries the huge responsibility of protecting U.S. presidents and their families. Photojournalists like Jacquelyn Martin of The Associated Press get to tag along and photograph the work the service does in the background.
"In my time covering the White House the U.S. Secret Service and its visual alphabet of dark suits, sunglasses and earpieces has fascinated me," Martin wrote on a recent AP Images Instagram post.
Martin curated a selection of her photos from over the years and posted them in stark black and white to her Instagram, allowing us to see the Secret Service blend in at work.
See the photos from Jacquelyn Martin's series below: