Mining operations would usually be shut down during the summers when coal was not needed for heating of the homes. The miners had a hard time making a living with such part time work. The railroads gradually switched to diesel engines for locomotion and home heating was converted from coal to natural gas. The coal was of poor quality and mines could not compete commercially. It was also quite costly to get it out of the ground because the seam of coal was only about three and a half foot thick. Most of the later mines were truck mines for local markets. Mine after mine was closed throughout the first part of the 20th century.
The Gladstone Mine was the last to close in March, 1971 in conjunction with the reconstruction of Highway No. 2, including the modern railroad viaduct. The closing of the mine ended an era, not only in Appanoose County, but all over Iowa. The Gladstone Mine was the last pony mine operating in the country.
Before the mine was completely closed and sealed, Iowa State College in Ames came out and made a 23 minute videotape of the mine operation, including the ponies pulling a load of coal to the top and the trip mechanism to unload the coal. It is very dark in the mine in spite of the carbide lamps on the miners‚ caps and it is very difficult to take pictures. The ponies in the film happen to have a white blaze on the front of their faces which show up as soon as the ponies approach the surface daylight. This tape is now available for viewing at the Centerville museum.
Former workers in that last pony mine re-opened the mine and started the machinery long enough to make the film. They were people like Louie Noble, Charles Fox, Joe Bunyan and Frank (Chesco) Massa. The mine was owned by Wayne Arbogast of Numa.