Dunbar made multiple versions of the No. 1 Wagon from 1900 to 1930. 
The last one was sold on June 11, 1930 
to L. A. Tucker of Hollywood, California

No. 1 Wagon
1905 Catalog

One of the few pictures of the rear side of any early Dunbar Popcorn Wagon. 

No. 1 Wagon
1906, 1907, 1911, 1913, 1915, 1920, 1922, and 1926 Dunbar Catalogs

This is the first catalog with the little man called Happy Hooligan  The catalog is marked as a 1906 Catalog.  However, we have a copy of a 1904 letter that says Dunbar added Happy Hooligan to their machines in 1904.  So the catalogs are marked later than they were published or it took Dunbar a couple of years to get a picture of their new model. Note the steam engine base now has wings and the whistle has been moved closer to the steam engine.

No. 1 Wagon Wooden Wheels
1905 and 1906 Dunbar Catalogs

No. 1 Wagon - Wooden Wheels
1907, 1911, 1913, 1915, 1920, 1922, 1926, and 1929 Dunbar Catalogs