The Post Office Oak in Council Grove, Kansas, served wagon trains from 1825 to 1847 as cache for mail. Believed to have been 270 years old when it died in 1990, this Bur Oak was an unofficial post office on the Santa Fe Trail. Passing pioneers could leave messages for future travelers in the base of the tree. The stone building was erected in 1864 for use as a brewery. Today, the Morris County Historical Society operates a museum here.