The Senate Committee on Intelligence released a highly redacted report saying that Russia hackers targeted the voting systems of all 50 states during the 2016 elections, and while there is no evidence of tampering, it’s clear that they could have altered votes in some systems.
The original report from the Senate can be found on the official website at:
https://www.intelligence.senate.gov/sites/default/files/documents/Report_Volume1.pdf
Learn more from these news articles:
New York Times
https://www.nytimes.com/2019/07/25/us/politics/russian-hacking-elections.html
Washington Post
https://www.washingtonpost.com/opinions/2019/07/30/high-level-senate-report-confirms-it-our-elections-still-arent-safe/?utm_term=.ec22bd2e139b
Vanity Fair
https://www.vanityfair.com/news/2019/07/senate-report-russia-2016-election-50-states