The Metro Transportation Library & Archive’s collection on Flickr now contains more than 7,500 historic images and continues to grow.

Numerous photographs from the Pacific Electric (“Red Car”) and Los Angeles Railway(“Yellow Car”) systems shed light on our transit history and what was once the largest streetcar system in the world.

This week, the Library & Archive takes a closer look at a 1940s-era Los Angeles Railway booklet containing not just historic photographs, but construction specs for nineteen different types of streetcars that rode the rails in central Los Angeles seventy years ago.

The entire story unfolds over at the Primary Resources blog, including links to the entire set of newly discovered photos and specifications.