Los Angeles MTA
December 2012
Red / Purple Line Subway - 158,830
Blue Line LRT - 91,709
Expo Line LRT - 23,193
Green Line LRT - 46,029
Gold Line LRT - 42,295
Total Rail - 362,056 - Dec 2012 (for comparison sake, Dec 2011 was 294,082 and Dec 2010 was 270,199)
With the Expo Line Phase 2, Gold Line Foothill Extension, Crenshaw Line, Downtown Connector all under construction, i expect LA to break the 500,000 barrier by 2016
Source -
http://www.metro.net/news/ridership-statistics/