Welcome to Mifflintown Borough Mifflintown Borough is the County Seat of Juniata County. It is a rural area with a population of 861 residents(census 2000). We are mainly an agricultural area situate west of Harrisburg off of Route 22/322. News & Notices Recyling02/14/2023There is no more curbside recycling in Mifflintown Borough. Residents can recycle if they choose and take their recycling to READ MORE