Does "one stop" registration and voting increase turnout?

Making valid turnout comparisons between states with different citizenries, political cultures, and electoral rules and machinery is hard to do. But that doesn't people from making them, and making them poorly.

The story below is a typical example. The analysis was provided by "Democracy North Carolina" in this report report. As described in the story:

In other states, it has been shown to improve turnout.

During the 2004 election, voter turnout was 41.9 percent nationwide for residents aged 18-24. It North Carolina, it was 38.4 percent.

But in the six states that had one-stop voting, an average of 56.1 percent voted.

These six states are: Minnesota, Maine, Wisconsin, Idaho, New Hampshire and Wyoming.

Is there anything else about these states that might lead them to have higher than average turnout? I'm not sure, and I'll do some research on the topic.

What surprises me is how widespread these claims are. A quick Google search on "same day registration turnout" leads to the same claim made by Demos USA, The Alliance for Better Campaigns, and The Centrist Coalition. Many seem to rely on a report from Curtis Gans issued after the 2000 election.

Never is it made clear whether "Same Day Registration" was entered into a full, multivariate model of turnout to see if it makes a difference above and beyond demographics and other rules and procedures, or whether it is the case that these states already had a participative political culture and adopted same-day registration as a consequence.

As a final aside, Democracy NC says they found out the "less than 2%" of young North Carolinians knew that they had to register 25 days before election, and that less than 10% were "close" (within 4 days).

Their press release claims that this shows that "even the young people who were registered and voted struggled with the questions about registration, such as the registration deadline..."

Do we have any evidence at all that this is true? How many registered voters (of any age) do you think know how many days, exactly, before an election they need to register? Don't most folks just register once during a registration drive or when they register their motor vehicle? Why is this something that we think people should know and why do we think it has any bearing at all on turnout.

The major barriers to turnout are voter interest and motivation. Election reforms are fine as far as they go, but if anyone thinks that minor tweaking around the edges, like same day registration, will do anything but help turnout a few percentage points, they are sadly mistaken.

Referenced Story: News 14 Carolina | 24 Hour Local News | LOCAL NEWS | One-stop voting might be approved