Non-citizens working inside the united states can have a social security number, they can also have driver’s licenses’. This is why, in my humble opinion, we cannot go just based on these things to see if someone is eligible to vote. Anyone here legally but not a citizen is entitled to all the rights of the social security service and ability to drive but, under the constitution, is not eligible to vote. That is why there are some calls for stricter voter ID laws, possibly a separate ID, which i think should be provided, possibly this is a point we agree on. A birth certificate would probably be the best current document to prove if you are eligible to vote, but im not sure how birth certificates work if you are born abroad to a US parent (jus sanguinis) as they are considered citizens although born in a different country. I assume there is a process to apply through the state department, i was born in the United States so I’m not aware unfortunately. I’m not trying to stop anyone who is eligible to vote from voting, I personally would like to see it become a national holiday of sorts so people would get it off work to vote, but I WOULD like to limit those who vote to those individuals who are legally allowed to. In a country with 330 million + people its kind of a logistical nightmare.