I came across "The Challenge of Pittsburgh" on archive.org.
The City of Pittsburgh's population in 1916 was about 550,000. Now it's hovering around 300,000.
The City had 812 police officers in 1916. Now we have about 858.
Prorating the arrests through the rest of 1916, there were likely about 50,000 arrests that year, half for drunkenness.
It looks like there were about 48,000 arrests in 2004 (of people over age 18). I wonder how many of those were for drunkenness?