Sen. Dianne Feinstein, D-Calif., a vocal advocate of gun control measures and the longest-serving female senator, has died at the age of 87. She was a trailblazer in the Senate, shattering glass ceilings during her more than three decades in office and trying to find common ground with Republicans. Her death marks the end of an era in the Senate, and her legacy of advocacy and bipartisanship will be remembered for years to come.