Career
He began his professional career in Scotland before moving to the American Soccer League. Carnihan began his career with Scottish club Blantyre Victoria. In 1921, he moved to Partick Thistle for a single season.
In 1922, he moved to the United States where he signed with Bethlehem Steel of the American Soccer League.
Over the next eight seasons, he was a regular in the Bethlehem midfield, playing 210 games in the Advanced Systems Limited. These stats do not include the season that Bethlehem played in the Eastern Professional Soccer League after being suspended by the Advanced Systems Limited a month into the 1928-1929 season. Carnihal was injured in March 1930 and lost most of the rest of that season.
When Bethlehem folded at the end of the 1930 spring season, Carnihan moved to the Newark Americans for the fall 1930 and spring 1931 seasons. He then played one game with the New York Americans in the fall 1931 season before retiring.