Highway vibration

I drive a 2002 Honda Civic with 94,000 miles. Recently when I reach speeds of 65-70mph (or higher) there is a distinct vibration every 3-5seconds. I feel it mainly in my hands through the steering wheel but it is noticeable throughout the car.

I would appreciate any help in diagnosing the cause of this vibration before it shakes my car apart!

Start first with simple wheel balance check. A DIY method is to rotate the tires yourself and see if changes.

Sounds like a tire ballance issue. Might want to check your tires to see if there is a bulge in one or more them, too.