PA 77 begins at an intersection with PA 27 in the city of Meadville in Crawford County, heading northeast on two-lane undivided Hickory Street. The road passes homes, crossing into West Mead Township and becoming Blooming Valley Road. The route runs through rural residential areas before continuing into a mix of farmland and woodland with some homes, heading into East Mead Township. PA 77 becomes unnamed and runs through more rural areas, passing through a corner of Woodcock Township prior to entering the borough of Blooming Valley. Here, the road becomes State Street and passes a few homes, reaching an intersection with PA 198. The route heads back into agricultural and wooded areas with some residences as it crosses into Richmond Township. PA 77 becomes unnamed and passes through more rural areas, running through New Richmond before forming a brief concurrency with PA 408. The road heads into Athens Township and passes through Little Cooley before crossing Muddy Creek in a wooded area.