The Pew Center on the States (PCS) focuses on military and overseas voters as part of their Election Initiatives. The PCS website describes this key program and the Election Initiatives' recent research reports.

Military and Overseas Voting Initiative
The Military and Overseas Voting Initiative is a core PCS program to improve U.S. elections. Specifically, this initiative  addresses the complex process facing military and overseas citizens attempting to register to vote and cast their absentee ballots. The summary highlights challenges that these voters currently face and offers solutions.

No Time to Vote: Challenges Facing America’s Overseas Military Voters
A third of  U.S. states do not provide enough time for military personnel stationed overseas to vote, and half of all states and the District of Columbia need to improve their absentee voting process to ensure that the votes of servicemen and women abroad will be counted. This report is the first-ever detailed public analysis of states’ voting systems for military personnel stationed overseas.

Overseas Voting: Challenges and Innovative Research
A report by Pew’s finds that states have adopted inconsistent processes and requirements for overseas voters, making it difficult for them to participate in the electoral process.