because I was driving solo. You can follow my route. Click to embiggen and see how many national parks I skirted while driving Interstate freeways 405 to 105 to 605 to 210 to 15 to 70.
I left Los Angeles at 12:00 PDT yesterday and arrived in Denver at 19:00 MDT today. My 1000 mile route crossed sections of California, Nevada, Utah and Colorado. Try doing that with only state and local roads. The federal interstate highway system is an engineering marvel and an economic boon.
I found a YouTube video of just one of the stunning sections I travelled these past two days.
Although the desert southwest and the rocky mountain range are both stunningly beautiful, they pose uniquely different--but extreme--climatic and geologic challenges for road builders. I am just in awe of the natural scenery, and the human imagination, skill and willpower that it took to raise the money and build these highways.