In 1927, the TTC took over the operation of the Mimico line and extended its service eastward to Roncesvalles Avenue.

On 16 July 16, 1892, the Toronto and Mimico Electric Railway and Light Company (incorporated November 14, 1890) began initial service between Sunnyside and the Humber River.

[3] On June 13, 1897, the line started Sunday service,[2] helping to increase summer excursion traffic.

[4][5] West of the Etobicoke Creek, the line was on the south side of Lake Shore Road.

[6] A trip from Port Credit to Yonge Street would take 2 hours and cost 18 cents.

[7] On January 12, 1927, the Toronto Transportation Commission started operating the T&YRR lines under contract.

[6] On May 9, 1928, the Beach streetcar route was extended west to Humber Loop evenings, Saturday afternoons and Sundays, overlapping Mimico radial service.

[8] On October 28, 1942, during World War II, a temporary double-track streetcar extension went into service from Long Branch Loop west to an armaments factory.

Roughly following the route of the defunct Port Credit radial line, the "Small Arms Extension" ran for.33 mi (0.53 km) on the north side of Lakeshore Road over Etobicoke Creek via a highway bridge and terminated at a loop near the factory.