美國有選舉人登記製度，選民首先需要登記才能投票，隻有美國公民才能在聯邦選舉中投票。如果通過郵寄登記或者以前從未投票，則必須出示ID才能登記。這個是聯邦法律的規定，適用於全部50個州。
至於投票時是否需要出示ID ，這個要求是州法的範圍。有14個州在投票時不需要出示ID，但需要通過其它的方法證實自己的身份。注意一下這14州中，有4個並不是所謂“民主黨州”，所以樓下情緒化的聲稱“民主黨不讓用ID”是缺乏基本的常識。
In the remaining 14 states and D.C., voters can cast a ballot in person on Election Day without showing an ID document. These states have "non-documentary" ID requirements, meaning voters must verify their identity in other ways, such as by signing an affidavit or poll book, or by providing personal information. All states have procedures for challenging voter eligibility.
Below are details on the statutory requirements for voter verification in states with non-documentary ID requirements.
Voters' Responsibilities
The three main types of non-documentary ID requirements that voters may be asked to satisfy are:
Affidavit: Voters sign an affidavit asserting their eligibility to vote and/or awareness that falsely claiming eligibility is a criminal offense. Illinois includes the full text of its affidavit in statute. Other states provide partial texts or general guidelines.
Signature: Voters must provide elections officials with a signature before casting a ballot. In most cases, this involves signing a poll book or voter registration list at the polls but there are some exceptions. For example, Oregon voters must sign the return envelope included with their mail-in ballots.
Biographical information: Voters may also be asked to provide personal information, either verbally or in writing, at the polls. In most cases, voters are asked to give their names and/or addresses. Under certain circumstances, Maryland, New Mexico and Minnesota, ask voters to provide full or partial birth dates.
加州選民登記和投票時的ID要求，可以在下麵這個文件裏找到。即便是加州這種基本不要求VOTER ID的州，對於某些選民在投票時也是有ID要求的。
