In the original canon, Kara Zor-El came to Earth in 1959 after the domed Argo City, which had been thrown clear of the explosion of Krypton, stared emitting radiation dangerous to its inhabitants, even though they weren't exposed to the rays of a yellow sun and thus having super powers (Kryptonite can't hurt a non-super Kryptonian, so this was some form of anti-Kryptonite). As in Kal-El's origin, there was just room in an experimental rocket for one person, young Kara, Kal-El's cousin. Her father Zor-El had been able to monitor Superman's activities on Earth and so not only launched Kara there, but created a costume for her similar to her heroic cousin's.
Superman, upon Kara's arrival and after hearing her story, decided to send her to an orphanage (no such thing as foster families in the late 1950s I guess), telling the administrators that her name was "Linda Lee" and her family had been killed in a flood that destroyed her home town (no records). She hid her identity under a brunette wig and only used her powers in secret. Superman felt she needed practice before doing heroics publicly.
The cover below shows the day, three years later, when Superman decided to tell the world about his younger, Kryptonian cousin, the day when Supergirl became a hero in the light rather than in the shadows.
Eventually, Kara/Linda was adopted by the Danvers, a childless couple (no older sister like in the TV show).
Thought folks might enjoy the look back.
