Excerpt, the Russian lady described below was registered for the Democrats (she didn't do it) in SF even before she became a citizen in 2012:
Noncitizens across U.S. find it easy to register to vote, cast ballots
Russian national surprised to be on rolls in San Francisco
...
The Washington Times obtained a San Francisco County voter log that detailed Ms. Shuvalova’s registration history and presented the document to her.
It showed that she signed up as a Democrat in July 2012 and that her registration was canceled in May 2016 after she told election officials she wasn’t a citizen. Her registration, as a Republican, was reactivated in March 2017.
“This is definitely a shocker to me. It is like an identity fraud because this is not coming from my end,†said Ms. Shuvalova, who now lives in New York, works as a personal trainer and calls herself a Democrat. “Like I told you, I haven’t even been a citizen during that time frame. So what can we do about it?â€
Read more at: https://www.washingtontimes.com/news/2018/jul/31/noncitizens-find-it-easy-register-vote-cast-ballot/