Crews will start resurfacing a portion of the road between Little Creek Road and Route 488 in Jackson, Lancaster and Muddy Creek townships and in Portersville Borough.
Work has already started on a different paving project on Route 19- this project happening further south just over the Butler County line in Allegheny County.
PennDOT says there are currently no plans to address potential traffic issues caused by the Route 19 work.
An $8 million improvement project to Route 228 in Adams Township is already underway.
Most of the work will take place overnight between 8 p.m. and 6 a.m.
In Winfield Township, crews are working on replacing a bridge.
The West Winfield Bridge- which runs over Rough Run- is being worked on. Drivers will see traffic down to one lane on Winfield Road, between Clearfield and Cornplanter roads.
The project should be done in November.