It's not really a 1:1 match. Any foreigner who has ever worked in the US has one too (me included). Plus voter registration also covers subnational elections, which SSN data would not help with.
Re: the draft - if you are eligible for it you have to register to it, just like voter registration except it's mandatory. If you don't register for selective service you can't get federal college loans IIRC. You also have to register for the draft to apply for a green card?
Re: the draft - if you are eligible for it you have to register to it, just like voter registration except it's mandatory. If you don't register for selective service you can't get federal college loans IIRC. You also have to register for the draft to apply for a green card?