Before 1940, Nobel Prizes were a reflection of the rapidly evolving state of science. It was uncommon for an award to happen for a discovery 20 years or more after the research happened, it seemed more like a concession prize because nothing had happened recently - in physics, chemistry and medicine, delayed awards only occurred 11%, 15% and 24% of the time.
By 1985, those percentages were 60%, 52% and 45%. This is only a problem that has cropped up in science and medicine, other prizes are quickly awarded on pop culture status; President Obama was apparently given one, based on when nominations happen, for his first inauguration speech.