Timing-Yellowstone/Rocky Mtn Parks

[gearhead]

Planning a trip. I want to attend USAC races at Belleville Kansas July 30-Aug1. If I'm driving that far, I may as well go somewhere else too.
"in for a dime, in for a dollar"
From Belleville, Yellowstone is a 2 day drive, Rocky Mtn is 1 day. It's been 30 years since we've been to either. May do both, or just one.
That said, I need advice regarding timing. Would the last 2 weeks of July be better than the 1st weeks of August? Concern is mostly crowds. Is there much difference? Much weather difference?

[Western Traveler]

As far as Yellowstone goes not much difference the bracket of time you are using is the height of the season. Weather wise it can snow any month of the year but even if it did the weather would change soon enough. That is a great time of year and I would expect warm days. If I was making the trip I would make reservations for a site outside the Park and know I had a place to stay (I favor the town of West Yellowstone but I know that is at the opposite end from your approach) but people are coming and going at the campgrounds every day. There is a phone number the Park Service has that is updated throughout the day for campground availability. Usually full by 2 PM.
It is an enjoyable trip in the right frame of mind knowing you will be going everywhere inside the Park SLOW. If one remembers the first time they saw a herd of buffalo and their reaction to it, it makes it easier when you are blocked on the road the thirtieth time by someone seeing them for the first time. Then of course road repairs and construction takes place in the summer when things aren't frozen.
The speed limit is around 40 but you might not see that much.

[Jca3]

The weather is great but it is peak season. Make reservations now or you won't get a spot in the parks. We like staying in the Tetons - Signal mountain if you aren't too long. In Yellowstone Mammoth Hot springs campground is pretty nice. We have also stayed at Fishing Bridge and Madison campgrounds but they cram you in like sardines. Not very enjoyable. We like a little space between our slide and the side of the next trailer.