Canada announced retaliatory tariffs on $27.6 billion in U.S. goods, escalating the trade war with Washington. The Supreme Court issued a temporary win for President Trump regarding his order to restrict mail-in voting, though lawsuits continue. Meanwhile, South Carolina Republicans hold a special Senate primary runoff, and health officials report the first U.S. measles deaths of the year. A new study also reveals that at least 25% of deceased NFL players had CTE.