Hallinan began his baseball career in with the amateur Aetna Club of Chicago, and played shortstop for four seasons with that club. During that stretch, he played a few professional games for the Fort Wayne Kekiongas of the National Association.
Major leagues
Hallinan did not play professional baseball again until he joined the Westerns of Keokuk, Iowa in. He played every inning of their 13 games at shortstop and, when the Westerns folded, moved on to the New York Mutuals for the remainder of that season and all of 1876, when the Mutuals were a founding member of the National League. With two home runs, he was third in the NL in that category. With three in 1875 he had ranked fourth in the NA. The Clipper observed that he, "being remarkably fleet of foot, was often credited with home runs." Jimmy playing sparingly for the Cincinnati Reds in. When the Reds disbanded during business troubles, it looked as if the team was going to fold; he and Charley Jones agreed to sign and play with the Chicago White Stockings. The Reds eventually corrected their situation, and rightfully asked for their two players back. It was agreed between the two teams that Jones return to the Reds, and Hallinan was to remain with the White Stockings. It was during July of that season that Hallinan became too ill to play, which forced him to quit, but did return to the field later in August for the Indianapolis Blues. He was only able to participate in three games. Although he was a better than average hitter, he lacked skill in the field. For his career, he hit.287 in 170 games, but in his 111 games at shortstop, he totaled 161 errors for a.744 fielding percentage. He didn't fare much better in his games in the outfield or at second base, as his career total was.756. Early in his career, he spent most of his playing time at shortstop, but due to his lack of fielding skill, he was later moved to the outfield.
Death
It is alleged that the reason Jimmy became too ill to play was most likely due from overuse of alcohol. In October of the following year, he succumbed to inflammation of the bowels, dying at 30 years of age in Chicago, and he was interred at the Calvary Catholic Cemetery in Evanston, Illinois.
