Welsh's political career began in 1917 when he was elected to the State House representing Kent County, where he served until 1924 and as Speaker in his final two years.

Alex J. Groesbeck selected Welsh to be his running mate for his successful campaign for Governor of Michigan in 1924.

Welsh attended the Republican National Convention in Cleveland that year which nominated Calvin Coolidge for President of the United States.

[2] When he served as the city manager of Grand Rapids, Welsh masterminded the construction of the pool at Richmond Park.

His plan preceded Franklin D. Roosevelt's New Deal and came to an end when federal programs became available.