All US roadways are designed with rain run-off in mind leaving the highest point in the center and allowing the rain to run off towards the ditches. This is something you should keep in mind when installing your receiver pin. Always insert the pin on the driver's side of the receiver tube so if something were to happen to the cotter pin the vibrations of the road will drive the pin further in place. Instead of allowing it to fall out. This is also why when towing you should routinely check your towing set-up. Another way to combat this problem is by checking out one of CURT's lockable receiver pins.