In 1912 there was a complete revamping of the street numbering system to make it more standard throughout the City of Grand Rapids. If you are looking for someone in the city directory before 1912, and after that date, the street number could easily have changed but the person was living in the same house as before the change. In the case of the following avenues and streets, the change would be not only the number of the address but also the street name itself.