After the war, Straus became Assistant Editor of the New York Globe, but left in 1920 because of the paper's support for Republican presidential candidate Warren G. Harding. Instead, he entered politics as a Democrat, and was a member of the New York State Senate from 1921 to 1926, sitting in the 144th, 145th, 146th, 147th, 148th, and 149th New York State Legislatures. He chaired the Committee on Agriculture from 1923 to 1924.
He was New York State Administrator of the National Recovery Administration in 1934; a member of the New York City Housing Authority in 1936; and Administrator of the United States Housing Authority from 1937 to 1942. He published two books on housing issues: Seven Myths of Housing (1944), and Two-Thirds of a Nation – A Housing Program (1952).
Straus was chairman of the WMCA radio station until his death.
When Straus attended Heidelberg University in 1908, he met a young art-history scholar named Otto Frank, who was the same age as him. The 20-year-old Frank accepted a job at Macy's, where he fell in love with New York and its brashness, but he returned to Germany after his father's death in 1909.
Frank, who was Jewish, later fled Germany with his family in the face of the severe antisemitism of Nazi Germany. They relocated to Amsterdam, where Frank enlisted Nathan Jr.'s assistance to help his family obtain visas to move to the United States. Despite receiving help from Nathan Jr. and other connections, the Franks were unable to gather all the needed paperwork before Nazi Germany ordered US consulates to close in German-occupied territory (including the Netherlands).[5] Ultimately, the entire Frank family was interned in Nazi concentration camps, with Otto the only member to survive the war.
In the years that followed, Otto published the diary of his daughter, Anne Frank, which described the family's life in hiding from the Nazis in Amsterdam. That work, known in English as The Diary of a Young Girl or The Diary of Anne Frank, is one of the best-known books about the Holocaust. It has been translated into dozens of languages and adapted into plays and films.