The speed limit on two lane highways in Iowa is 55 miles per hour. Not 65 like South Dakota or 60 in some other states. However, 60-65 mph has become the norm in Iowa, due to a lot of roads and "lax" enforcement of the speed limit.
I normally drive 60-62 on most rural roads. That's a nice comfortable speed. With proper planning I avoid most small towns and can average an actual speed of between 50 and 55 miles per hour and a fuel mileage around 24 mpg with a four wheel drive pickup.
But, lately traffic has been in ultra high speed mode. People are driving 65-70. They pull up behind and follow as close as possible and pass in the stupidest places. Passing while coming into a small town with children playing is DUMB. Passing going up hill and on curves.
If you wish to kill yourself, that's entirely up to you. But those children don't want to be involved and neither do I.