SH 119 starts at US 6 in Clear Creek Canyon east of I-70. The intersection is a signalized T, with people coming east on US 6 turning left to Black Hawk or right to Golden. From there SH 119 follows North Clear Creek up to the gambling towns of Black Hawk and Central City. SH 119 is always packed with casino buses. SH 119 continues north, with numerous switch backs to Rollinsville, and north of there hits SH 72. They are concurrent north to Nederland, where SH 119 breaks off and goes down east, via Boulder Creek & Boulder Falls, to Boulder.
At the mouth of the canyon, SH 119 is immediately in Boulder. It goes east to downtown on Canyon Blvd., and at Broadway hits SH 93. SH 119 continues east along Canyon, and at 28th St. hits US 36 where SH 119 turns north. SH 119's overlap with US 36 actually is somewhat marked. They are together for about one and a third miles, and then SH 119 breaks off and goes northeast via Diagonal Highway. From there, SH 119 is expressway all the way to Longmont.
SH 119 and SH 157 meet at an interchange on the northeast side of Boulder. The way the interchange is set up, one goes flying through from 119 west to 157 south (plus the reverse movement) without any hindrances. However, taking SH 119 through the interchange means going through a set of signal lights. Coming east on 119, one merges onto the traffic coming north off of the northbound 157, while going west on 119 requires taking an exit.
From SH 157, SH 119 continues northeast as divided expressway toward Longmont. This is a very busy and important stretch of highway, and CDOT expects traffic to keep increasing. The speed limit fluctuates between 55 and 65mph, due to several sets of signal lights. What makes this section of SH 119 interesting is that the median is very wide in some places. No, there's nothing in the median except for scrub grass. Consequently, any cross road that has signal lights with SH 119 has two separate set of lights.
The SH 119 expressway continues northeast to Longmont, where it warps down to a multi-lane city street, Ken Pratt Boulevard. At Florida Ave. it curves east and goes to Main St., where it hits US 287. SH 119 goes across US 287, turns back into a divided expressway, drifts northeast toward the Boulder-Weld county line, then heads due east to I-25. The interchange at I-25 Exit 140 is a large diamond interchange. It's unofficially known as Del Camino, in reference to a restaurant that used to be there at the SH 119/US 87 intersection.
