Your correspondent Mr George (Motor Sport, May 1988) is not quite correct in what he says about the speed limits in the USA; although all States introduced a 55mph speed lirnit, only 38 of them have raised this to 65 and then only on "rural interstate highways".
Mr George refers to the safety aspects of these limits. From May to July last year, traffic deaths on these rural interstate roads in 22 states which raised their limit increased by 52% as compared with the same period in the year with the lower limit. By contrast, deaths on all other roads in those states fell by 10%. In seven states which retained the 55mph limit, deaths on the rural interstates rose by only 10%. Deaths on all other roads in those seven states fell by 2%.
However unpalatable it may be, it certainly appears from these and other data that higher speed leads to more collisions.
J G Millward