Our I-5 exploration continues, with a focus on the segment of I-5 from the US 101 split in Downtown Los Angeles to the Route 99 split in Wheeler Ridge. This episode, Part 1 of 3.06, after a recap on LRN 5 and Sign Route 5, focuses on the history of I-5 from Downtown LA (DTLA) to and through the Newhall Pass. We explore the history of LRN 4 and LRN 161, the timeline of freeway construction to and through Burbank, the history of Route 5S (Colorado Blvd), and a dive into the history of routings through the Newhall Pass and in Saugus. We also talk about the Interstate number submissions for I-5, and have some updates on the projects we discussed in Episode 3.05p2. Our special guest this episode is Sydney Croasmun of the Ridge Route Preservation Organization. Sydney brings her expertise to our discussion in Part 2, when we're going in detail over the Ridge Route. Part 2 also discusses projects and naming in this section, especially the history of the "Grapevine" name. Subsequent episodes will be looking at (3.07) the Westerly Routing; (3.08) the planned I-5W; (3.09) the former US 99W portion from Sacramento to Redding; and (3.09) the portion from Redding to the Oregon Border. For more details, including additional links, visit this episode's page on CARouteByRoute.