I think the line started around 3k or 4k breweries across America around 1900, reached an all-time low in the 1970-1990s and now were back up to where we started.
Of course, the story here is refrigeration. When refrigeration was not common place, you needed a lot of breweries near consumption.
I'm also thankful for the variety of beer options we have today.
edit: this might have been the image I remember - but theres no data source mentioned: https://vinepair.com/wp-content/uploads/2015/11/historical-b...