Federal investigators have discovered an underground tunnel stretching between Tijuana and San Diego that was allegedly used by Mexican drug cartels to traffic cocaine into the United States. NewsNation's Ali Bradley reports on the passageway, which one cartel expert says has been a common tool used by transnational criminal organizations for years. #cartels #cocaine #Mexico Get a fast-paced look at the latest from the border to Main Street to the White House on "NewsNation Live" with Connell McShane. Weekdays starting at 3p/2C. NewsNation is your source for fact-based, unbiased news for all Americans. More from NewsNation: newsnationnow.com Get our app: trib.al/TBXgYpp Find us on cable: trib.al/YDOpGyG How to watch on TV or streaming: trib.al/Vu0Ikij