Kammala wannan magana: Bayan barin Majalisa, O'Brien ya ci gaba da gudanar da harkokin kasuwancinsa. Ya yi aiki a matsayin wakili a Majalisar Dattijai ta Democratic a
A shekara ta 1916. Ya mutu a Brooklyn a ranar 2 ga Satumba, 1924, kuma an binne shi a Holy Cross Cemetery.