Corrections & Clarifications: A previous version of this article misstated the number of polling places closed in Maricopa County since 2012 and misspelled the name of Alex Gulotta.

Election officials in Arizona have closed hundreds of polling places across the state following a U.S. Supreme Court decision that struck down parts of the Voting Rights Act, a survey by civil rights groups has found.

The review published Tuesday focused on 13 states where the federal government exercised oversight of voting changes for decades until 2013, when the U.S. Supreme Court effectively gave local officials more leeway to open or close polling locations.

Election officials proceeded to close 320 voting sites across 13 of Arizona's 15 counties, according to the report by the Leadership Conference on Civil & Human Rights.

Most of those were in Maricopa County, where there were 171 fewer polling locations in 2018 compared to 2012, a reduction of about 25%, the report found.

At the same time Arizona has emerged as a battleground state with control of Congress and the White House on the line, Phoenix voters encountered long lines in elections during 2016 and computer glitches in 2018.

"For many people, these burdens make it harder and sometimes impossible to vote," said Leigh Chapman, director of the voting rights program at the Leadership Conference Education Fund, which compiled the report.

The way many Arizonans vote has changed, however.

Maricopa County has embraced vote centers, for example, allowing voters to cast ballots from any polling place in their county instead of requiring each person vote from their particular precinct.

"While the raw number of polling locations may be lower, the actual opportunities voters have to go vote in person are way bigger," said Maricopa County Recorder Adrian Fontes.

Voting by mail has also become more popular over the past several years.

Arizona saw turnout of nearly 65% during the 2018 election, which was unusually high compared to recent midterm votes. Turnout for recent presidential elections has ranged from around 77% in 2008 to 74% in 2016.

Arizona had second most closures

Arizona saw the second-biggest reduction in polling places of the states surveyed, falling only behind Texas, where there were 750 fewer polling locations in 2018 than in 2012. Georgia closed 214 polling locations, Louisiana closed 126, Mississippi closed 96, Alabama 72, North Carolina 29, South Carolina 18 and Alaska 6, according to the report.

All of the states previously fell under Section 5 of the Voting Rights Act, which allowed the federal government to block local governments with a history of discrimination from changing election policies in ways that could disenfranchise people of color.

That system effectively came to an end with the U.S. Supreme Court's decision in a lawsuit by Shelby County, Alabama, arguing such provisions imposed an undue burden on local governments.

But civil rights groups saw the decision as dismantling years of oversight that were meant to protect the rights of people of color to participate in elections.

Changes in voting may have value for citizens, but counties have adopted such practices without the uniform standards or the analysis that previously was required by the federal government, said Alex Gulotta, Arizona state director for All Voting Is Local, an advocacy group that helped compile the report.

"What we do know is that, since 2013, there have been problems in every election," he said.

And not all counties with vote centers have closed large numbers of polling places, the report noted.

Navajo County, for example, has switched to vote centers but the number of polling places only dropped 4% from 2012 to 2018, according to the report.

Changes in Arizona counties

Here's the change in polling places in Arizona's counties from 2012 to 2018:

Apache County: 2% increase

Cochise County: 65% decrease

Coconino County: 14% decrease

Gila County: 48% decrease

Graham County: 50% decrease

Greenlee County: 38% decrease

La Paz County: 11% decrease

Maricopa County: 25% decrease

Mohave County: 49% decrease

Navajo County: 4% decrease

Pima County: 11% decrease

Pinal County: 2% decrease

Santa Cruz County: 29% decrease

Yavapai County: 17% decrease

Yuma County: 18% decrease

Andrew Oxford can be reached at andrew.oxford@arizonarepublic.com or on Twitter at @andrewboxford.