Llano, also known as Llano de San Juan is an unincorporated community located in Taos County, New Mexico, United States. The community is located on New Mexico State Road 73, 2.1 miles south of Peñasco. It was founded in 1796 after governor Fernando Chacon gave permission for settlement in the valley. A post office was operated from 1898 to 191…Llano, also known as Llano de San Juan is an unincorporated community located in Taos County, New Mexico, United States. The community is located on New Mexico State Road 73, 2.1 miles south of Peñasco. It was founded in 1796 after governor Fernando Chacon gave permission for settlement in the valley. A post office was operated from 1898 to 1914, and was then reestablished in 1925.