Highway Patrol is today seen as the father of the TV Cop show genre with it's all-action storylines involving the pursuit of murderers, bank robbers, smugglers and hijackers, by car, bike or helicopter across the highways and byways of the Western United States.

[...]

Its most enduring legacy was the introduction to the phrase 'Ten-Four', meaning 'message received and understood.'
[Television Heaven]

With hobbling gait, I almost make it back to my comfy armchair when the soles of my feet more than my ears become aware of that solitary, deep-bass, four-measure opening E-flat pedal, and my first thought is that something's gone badly awry with my stereo system. I mean, no opera can possibly begin like that. After assuring myself, however, that my stereo system is operating just fine, I start the LP going again, this time no longer intending to test my speakers, but intending instead to find out just what sort of opera it is that can begin in such an un-opera-like manner.
[AC Douglas, The Wagner Experience]