Robert was the Lake Mead National Recreation Area superintendent from 5-09-1942 until 4-22-1946.In 1938 he was a naturalist for the U.S. Park Service at Lake Mead. 

https://www.nps.gov/parkhistory/online_books/tolson/histlist7l.htm

Until her passing in 2017, Millicent (Siegel) Rosen was the living link to Benjamin “Bugsy” Siegel, one of Las Vegas’ most notorious links to the Jewish mob. A steadfastly independent woman herself, Millicent recalls Benjamin as a loving father to her and her younger sister. She is proud of his status as a Las Vegas visionary, though she affixes a footnote that the city of today might not be to his liking.