What smithb said.
Slater, Only half joking. The Portal bears are too comfortable around people - and vehicles. I recall Doug Sr posting from the Portal Store one day this past summer that he was currently watching several bears in the parking lot and a few more hanging around the trailhead. For hours. In the middle of the day. Take a good look at the exterior planking around the store windows - you'll see more than a couple of bear claw gouges. Bears congregate where the food is, and the Portal is by far the loudest dinner bell in the area when the summer crowds are present.
The good news is they aren't what you would consider aggressive - just very bold. Take the reasonable precautions with food, drinks and scented toiletries, and you should be fine. Just don't be surprised, though, if you encounter a bear (or two) when you hop out of your truck bed at 2 am to head for the bathroom. It is what it is. Ignore them, they'll ignore you.
And by the way, in summer you may find you have to park along the Portal Road because the lots are packed, especially on the weekend. People sleep there just fine too.
