Companies directly in trucking, as well as those that have an interest in it, are among many of the nation’s wealthiest public companies and are increasingly revealing their campaign-related contributions and political policies, and doing so voluntarily, according to The Center for Public Integrity

It reports a new study by the nonpartisan Center for Political Accountability and the Zicklin Center for Business Ethics Research at the University of Pennsylvania’s Wharton School, includes such names are United Parcel Service, Qualcomm, ConocoPhillips and CSX.

The study also found political spending by companies such as Cummins, Eaton, FedEx and Ford, among others, was made primarily through employee funding political action committees.

The Center for Public Integrity says the findings follow a 2012 election cycle in which nonprofit groups, fueled by corporate cash to a level unknown, spent more than $300 million to advocate for and against political candidates primarily through negative television advertising.

Last year’s presidential election was the most expensive in history and the least transparent when it comes to money, according to some.