The Federal Election Commission is an "independent regulatory agency," charged to "disclose campaign finance information, to enforce the provisions of the law such as the limits and prohibitions on contributions, and to oversee the public funding of the Presidential elections." The site has an entire section devoted to the 2016 Presidential Election.You will find campaign reports, maps, finance summaries and more.
OpenSecrets.org is an amazing site for tracking election contributions and spending. It provides figures for top contributors, contributions by industry, political actions committees (PAC), and donors, personal finances and travel expenses of the candidates and expenditures of the candidate's campaigns. This site tracks money given by geography, interest groups, and more. It also provides news stories about the candidates, legislation they have sponsored, and a breakdown of earmarks.