Bletz began the trip in Lansing, Mich., in mid-March. He has a crew helping him. Along the way, business and veterans groups help keep expenses low, he said.
He usually sits in the cage for six to eight hours a day, answering people's questions and educating the public.
AMVETS Commander Rusty Baker said the post was honored to have Bletz in Hagerstown.
"This town needs education," Baker said.
At one point Friday afternoon, two Hagerstown World War II veterans looked at Bletz's cage and praised him for his volunteer work.
"I think it is great. It makes people aware of what we went through," said Ken Kern, 84, of Hagerstown.
"The fact he is really showing what some of them had to do is fantastic," said Wallace Budd, 80.
While Bletz is a Vietnam veteran, he wants the public to be more aware and appreciative of all veterans, including those now in the Middle East.
Bletz served as a machine gunner for Bravo Company of the 1st Battalion of the 9th Marines in Vietnam in 1967. He received two Purple Hearts in combat, and was permanently disabled by shrapnel wounds to his foot, leg and back.
Bletz said too many Americans are unaware of the problems veterans face, including the families of POW/MIA soldiers. Among the issues he addresses are the quality of medical coverage and the amount of "red tape' veterans must negotiate with the government.
He is concerned that too many people forget or ignore what veterans have done, not thinking of them even on Veterans Day and Memorial Day, he said.
To many people, veterans are "out of sight, out of mind," Bletz said.
The cage reminds the public of what veterans endure, he said, and sparks media coverage of veterans issues.