Obviously the normal tools will not work.
Not very encouraging is it?
Now instead they could have included links to pages like this from the State of Oregon:
Oregon's homeless are able to vote. The voter must provide their current address of residence on the voter registration form. Residence is considered to be the place where the voter sleeps. This could include a shelter, a friend's home or other identifiable location. The mailing address of a person who is homeless or who resides where mail service is unavailable can be the office of the county clerk. The voter can always pick up a ballot at the county elections office.
But legally in most states there is not really a legal impetus on the Federal level to encourage voting.
...the right to vote in state elections is not expressly guaranteed by the United States Constitution. When the Constitution was ratified, most of the states required property ownership as a qualification for voting in a general election. Most of these voting requirements lasted at least until the Jacksonian era.' Although the states cannot deny or abridge the right to vote on account of race" or sex, "the States have long been held to have broad powers to determine the conditions under which the right of suffrage may be exercised."' In fact, the only thing that seems to require a state to extend the right to vote in state elections to anyone is the guarantee of republican government clause. Whether a par- ticular state government is a republic or not has been held to be a political question which the Court cannot decide. However, Congress would be certain to act if a state set up any government other than a republican government. In effect, the states are politically and historically bound to extend the right to vote to some of their citizens
Some of their citizens
Not all. And it seems the push has been for as few as possible.
But with this mobile economy do we really need to continue with the insistence of address possession? In this case the tumultuous economy does the dirty work for the Republicans by disturbing the lives of likely progressive voters. I'm certain there is a way around hijinks like income checks.
Here is some info on state by state rights.