Johnstonville first appeared as a
census designated place in the
2010 U.S. census. The whole population lived in households. There were 358 households, out of which 108 (30.2%) had children under the age of 18 living in them, 208 (58.1%) were married-couple households, 29 (8.1%) were
cohabiting couple households, 71 (19.8%) had a female householder with no partner present, and 50 (14.0%) had a male householder with no partner present. 56 households (15.6%) were one person, and 27 (7.5%) were one person aged 65 or older. The average household size was 2.72. The age distribution was 204 people (21.0%) under the age of 18, 75 people (7.7%) aged 18 to 24, 216 people (22.2%) aged 25 to 44, 276 people (28.4%) aged 45 to 64, and 202 people (20.8%) who were 65years of age or older. The median age was 44.3years. For every 100 females, there were 107.9 males. There were 403 housing units at an average density of , of which 358 (88.8%) were occupied. Of these, 289 (80.7%) were owner-occupied, and 69 (19.3%) were occupied by renters. ==Politics==