First, Hubble discovered redshifts. I don’t remember when.
Hubble's brilliant observation was that the red shift of galaxies was directly proportional to the distance of the galaxy from earth. That meant that things farther away from Earth were moving away faster. In other words, the universe must be expanding. He announced his finding in 1929. The ratio of distance to redshift was 170 kilometers/second per light year of distance, now called Hubble's constant.
