Most people tend to be comfortable at between 70 and 75 mph. After two decades of totally meaningless 55 mph speed limits, it should come as no surprise that the majority of drivers don't even think twice about ignoring whatever those little white signs have on them. Speed limits used to be an advisory. And in most of the rest of the country, they are again. The normal speed limit is 70 or 75 mph almost everywhere, with particularly dangerous stretches reduced accordingly.
Some states even have variable speed limits which change for weather conditions.
But here in Washington the speed limit remains at 55 mph. It is a feeble attempt by bureaucrats to reduce travel speed. And a totally arbitrary speed law will no more work than any other totally arbitrary law. The common citizen dismisses the law and it becomes the butt of jokes. The feeble enforcement does nothing to slow the speed of traffic but certainly engenders bitterment toward the police.