An investigation by the Indianapolis Star has found that policies by state and local Republicans in Indiana have restricted voting in predominantly Democratic areas — while expanding voting access in Republican-held areas.

At the heart of the controversy: early voting stations.

The investigation found that in Hamilton county, a Republican-majority area, officials had added two additional early voting stations, bringing the number of stations to one for every 100,000 residents.

However, in Marion County — a county that votes more Democratic, has a large African-American population, and includes Indianapolis, the state’s largest city — the Republican member of the election board has blocked additional stations and prevented the continuation of satellite sites that existed during the 2008 election (notably, when Barack Obama won the state.)

Election boards in Indiana have three people — a Democrat, a Republican, and the county clerk — and, since 2001, any decision to expand early voting requires a unanimous vote. The Republican member of the Marion county board has repeatedly blocked efforts to expand early voting since 2010.

In 2013, the Republican-controlled legislature passed a law (while Vice President Mike Pence was the governor) that specifically limited the processing of absentee ballots — which are used for early voting — to one site for counties with more than 325,000 people, without unanimous approval from the election board. In Marion, that meant one site for the more than 700,000 voters in the county.

Have the changes had an impact? The numbers speak for themselves. As Indianapolis Star’s Fatima Hussein writes:

The number of in-person absentee ballots cast in Hamilton County rose from 32,729 in 2008 to 53,608 in 2016, representing a 63 percent increase. At the same time, there was a 26 percent decrease in Marion County, from 93,316 to 68,599. During that period, the percentage of absentee ballots rose from 25 percent to 34 percent in Hamilton County, and fell from 24 percent to 19 percent in Marion County.

This Investigation comes in the midst of a lawsuit filed in May by Common Cause Indiana and the Indianapolis chapter of the NAACP against Republican officials. It alleges that the lack of voting stations in these areas constitutes discrimination.

Correction: An earlier version of this article misstated the name of the organization suing Republican officials.