Middle Arm, New South WalesMiddle Arm is a locality in the Upper Lachlan Shire, in the Southern Tablelands region of New South Wales, Australia. At the, it had a population of 377.DemographicsAs of the 2021 Australian census, 377 people resided in Middle Arm, up from 362 in the. The median age of persons in Middle Arm was 46 years. There were more males than females, with 53.5% of the population male and 46.5% female. The average household size was 2.7 people per household.