Which method of sharing data best enables others to quickly see trends in the data?

The best way of sharing data which enables others to see the trends in your data would most likely be using a scatter plot. When one uses a scatter plot this maximizes the ability to clearly depict the different kinds of trends to other people. 

Are you asking about a street map usage  if so here is your answer  a street map for a very limited area could simply be a bit map or a .jpg image.  but a more general map would probably store the streets as vectors.  but you shouldn't assume that there is one way to do it