Oregon= Portland as mentioned above, have had many births since the first Asian in the USA was born there in the 1960's. He was called 'Packy' and his mother was 'Belle'. 'Packy' is still there, one of three bulls. Their website(Portland Zoo) gives details & history of the three males and three females they currently have. You're correct, only one female has any potential for breeding and they seem to have now gone backwards re.breeding.
If you wanted to track what happened to all the others Portland or anywhere else has bred since, try;
Asianelephant.net- its a website with data - very up to date- on all Asian eles in captivity, breeding history, birthdates, deathdates etc, destinations of calves bred etc. If you can't find it, go through Leszoosdanslemonde- a french website, the same guy runs both of them.