If your vehicle is showing hood won't latch securely or visibly shakes at high speeds, here are the most likely causes and the parts you'll need to fix each one.
The hood latch is exposed to road grime, salt, and moisture, causing the internal springs and pivot points to rust and seize. This prevents the latch jaws from fully closing and locking around the hood striker.
If the vehicle recently had front-end bodywork, a radiator replacement, or bumper removal, the latch may have been bolted down out of alignment. The striker hits the latch off-center, preventing the primary lock from engaging.
Over time, the pivot rivets on the hood hinges can wear out, or the hinges can bend if the hood was forced closed over an obstruction. This introduces excessive play, allowing the hood to flutter and shake at highway speeds even if the front latch is secure.
A minor front-end collision or parking block impact can bend the radiator support where the hood latch mounts. Even a slight downward bend increases the distance between the latch and the hood, preventing a secure connection.