A 1904 map of the City & Suburban and the Portland Railway Co./Oregon Water & Power Co. trolley networks shows three large buildings designated as the "S.P. Car Shops" to the immediate south of 21st and Bush, around-abouts 23rd & Gladstone or so. Its worth noting that competitor Portland Railway/Oregon Water & Power ran the Hawthorne Line to the north and the Sellwood line nearby to the west on Milwaukie Street. That said, its a fair guess the intention of the Brooklyn line was to poach fares from the Brooklyn railyards, especially the adjacent shops.
Brooklyn Car 216.
In 1927 PEPCO folded the Powell & Bush sections of the line into the Bridge Transfer Line.
In the following photo we see a C&S-era "Brooklyn" trolley on downtown Morrison Street during the 1905 Lewis & Clark Centennial Exposition. The car is signed for "Powell & Car Shops."
City & Suburban Brooklyn Line Car 18 on W. Morrison c.1905
Note the near continuous line of cars waiting on the track, presumably heading northwest to the fairgrounds.