In 1902, Gillhaus was among the delegates elected from New York City to the state Socialist Labor convention in Utica.

[1] In August 1905, he was elected general treasurer of the Socialist Trade and Labor Alliance of the United States and Canada, and a delegate to the forthcoming convention in Chicago which would give rise to the Industrial Workers of the World (IWW or "Wobblies").

[2] Gillhaus was an active participant in what would come to be known as the first convention of the IWW, voted for the STLA to affiliate with the new organization, and was installed as a member thereof.

[citation needed] In 1912, as the VP candidate on the ticket with Arthur E. Reimer, Gillhaus got 29,213 votes.

In 1920, he was the Socialist Labor Party VP candidate on the ticket with William Wesley Cox.