The wound wasn't serious, and TR famously made his scheduled campaign speech before going to the hospital. Turns out it was a near thing for the former president, however.
According to the book The Attempted Assassination of ex-President Theodore Roosevelt, written immediately after the incident by Wheeler Bloodgood, Oliver Remey and Henry Cochems, "That the shot fired by Schrank didn't succeed in murdering Col. Roosevelt is a miracle of good fortune. A 'thirty-eight' long Colt's cartridge, fired from a pistol frame of 'forty-four' caliber design, so built because it gives a heavier drive to the projectile, fired at that close range, meant almost inevitable death.
"The aim was taken at a lower portion of Col. Roosevelt's body, but a bystander struck Schrank's arm at the moment of explosion, and elevated the direction of the shot. After passing through the Colonel's heavy military overcoat, and his other clothing, it would have certainly killed him had it not struck in its course practically everything which he carried on his person which could impede its force.
"In his coat pocket he had fifty pages of manuscript for the night's speech, which had been doubled, causing the bullet to traverse a hundred pages of manuscript. It had struck also his spectacle case on the outer concave surface of the gun metal material of which the case was constructed. It had passed through a double fold of his heavy suspenders before reaching his body.
"Had anyone of those objects been out of the range of the bullet, Schrank's dastardly purpose would have been accomplished beyond any conjecture."
TR composed a telegram to his family from the hospital was taken to after completing his speech:
"Am in excellent shape, made an hour and half speech. The wound is a trivial one. I think they will find that it merely glanced on a rib and went somewhere into a cavity of the body; it certainly did not touch a lung and isn't a particle more serious than one of the injuries any of the boys used continually to be having. Am at the Emergency hospital at the moment, but anticipate going right on with my engagements. My voice seems to be in good shape. Best love to Ethel."