It continues north through the village of Mid Gilpin to Rollinsville, where it crosses over South Boulder Creek and the tracks of the Union Pacific Railroad, on its way from Denver to the Moffat Tunnel.

The walls of the canyon are popular for rock climbing, and the scenic Boulder Falls is an easy walk from the highway.

The overlap with US 36 ends at the northern edge of Boulder where US 36 continues north to Rocky Mountain National Park, and SH 119 turns east becoming Diagonal Highway.

At an intersection with State Highway 157, SH 119 bends northeast, paralleling the tracks of the Burlington Northern Santa Fe Railway, and becomes an expressway with a very wide median, possibly intended to accommodate a future freeway.

East of US 287 in Longmont, a new expressway carries SH 119 directly to its northeastern terminus at a diamond interchange at Interstate 25 exit 240.

In 2003, a new expressway alignment for SH 119 was opened in Longmont, connecting directly from its intersection with US 287 to its terminus at I-25, bypassing the previous congested overlap with US 287.