Valdez is the 22nd person to hold the elected office since Webb County was established in 1848.
He was subsequently the county treasurer of Webb County from 1995 until his death.
El Cenizo is the third largest city in Webb County.
No Republican sought the position in heavily Democratic Webb County.
He died from natural causes due to heart disease, according to the chief medical examiner in Webb County.
Webb County is overwhelmingly Democratic and has voted for that party's electors since 1912.
Nearly 57,000 registered voters in Webb County did not cast ballots in the 2008 presidential election.
This was the only time since the early 1900s that Webb County had supported a Republican candidate for any office on a partisan ballot.
From 1935 to 1942, Salinas was an assistant district attorney in Webb County.
The city is the second largest in Webb County.