The American Mastiff was first developed by Fredericka Wagner of Flying W Farms in Piketon, Ohio. Walker developed the Mastiff by crossing an English Mastiff with an Anatolian Mastiff.
The selective breeding process took place over a span of many years. Wagner originally wanted to develop a Mastiff that would have less health problems and a longer lifespan. Another goal was tightening the lower lip line and creating a dry mouth.
After many years Walker achieved the American Mastiff and in 2000 the breed was officially recognized by the CKC.