February 4, 1920 – Groucho Marx marries Ruth Johnson in Chicago, Illinois.
February 14, 1921 – The Four Marx Brothers debut a new show, On the Mezzanine Floor (sometimes billed as On the Balcony), at Poli’s Capitol Theatre in Hartford, Connecticut.
April 1921 – The Four Marx Brothers make their first film, Humor Risk, at the Victor Studio in Fort Lee, New Jersey. The never-released film quickly disappears.
July 21, 1921 – Groucho and Ruth welcome their first child, Arthur Julius Marx, into the world. The Four Marx Brothers are appearing at Keith’s Riverside Theatre in New York, a short distance from the hospital.
June 19, 1922 – The Four Marx Brothers open at the London Coliseum. It is their first overseas performance.
October 8, 1922 – The Twentieth Century Revue starring the Four Marx Brothers debuts at the Englewood Theatre in Chicago.
January 27, 1923 – The Four Marx Brothers appear on a radio broadcast over WCAE in Pittsburgh, Pennsylvania. It is likely the first time they are heard on the new medium.
May 31, 1923 – The Four Marx Brothers appear in the first performance of I’ll Say She Is at the Lyric Theatre in Allentown, Pennsylvania.
May 19, 1924 – After a year on the road, The Four Marx Brothers bring I’ll Say She Is to Broadway. The show plays 313 performances at the Casino Theatre.
October 27, 1925 – The Four Marx Brothers’ new play, The Cocoanuts, debuts at the Tremont Theatre in Boston, Massachusetts.
December 8, 1925 – The Cocoanuts opens on Broadway, where it plays 276 performances at the Lyric Theatre. After Broadway the show toured until February 4, 1928.
May 19, 1927 – Groucho and Ruth are parents for the second time when daughter Miriam is born in New York City while the Four Marx Brothers are starring in The Cocoanuts at the Century Theatre.
February 9, 1928 – The Four Marx Brothers return to vaudeville as their new revue Spanish Knights opens at the Metropolitan Theatre in Los Angeles, California.
September 25, 1928 – The Four Marx Brothers debut their new play, Animal Crackers, at the Shubert Theatre in Philadelphia, Pennsylvania.
October 23, 1928 – Animal Crackers opens a 191-performance Broadway run at the 44th Street Theatre.
April 13, 1929 – A week after closing the Broadway run of Animal Crackers, the Four Marx Brothers return to vaudeville when Scenes from Animal Crackers opens a brief tour at the Madison Theatre in Brooklyn, New York.
May 23, 1929 – The film version of The Cocoanuts is released.
September 13, 1929 – Minnie Marx, the mother of the Marx Brothers, dies in New York City at 63.
September 20, 1929 – The Four Marx Brothers open a road tour of Animal Crackers at the Shubert Theatre in New Haven, Connecticut.