There is quite a story of how these blocks began showing up on barns.
A woman named of Donna Sue started what are now the oversized, brightly colored barn quilt squares appearing on barns throughout the Midwest and East. In Ohio in 2001, she made the first remodeled block of a barn quilt square in honor of her mother and to help a friend draw attention to his business from the nearby four-lane highway. In the nine years since, the modernized, oversized barn quilt squares have popped up as far East as New Jersey, with dozens of county and state quilt trails in between.
I know here in East and upper TN you will find blocks on most barns. There are many that people can stop and visit. To find out more just do a search for Barn Blocks.