@misc{ wiki:xxx, author = "Wikimedia Commons", title = "File:Maine Republican Presidential Caucuses Election Results by County, 2016.svg --- Wikimedia Commons{,} the free media repository", year = "2024", url = "https://commons.wikimedia.org/w/index.php?title=File:Maine_Republican_Presidential_Caucuses_Election_Results_by_County,_2016.svg&oldid=837595217", note = "[Online; accessed 5-July-2024]" }
\usepackage{url}
somewhere in the preamble) which tends to give much more nicely formatted web addresses, the following may be preferred:
@misc{ wiki:xxx, author = "Wikimedia Commons", title = "File:Maine Republican Presidential Caucuses Election Results by County, 2016.svg --- Wikimedia Commons{,} the free media repository", year = "2024", url = "\url{https://commons.wikimedia.org/w/index.php?title=File:Maine_Republican_Presidential_Caucuses_Election_Results_by_County,_2016.svg&oldid=837595217}", note = "[Online; accessed 5-July-2024]" }