Well, I am no Rachel Carson In fact, I am Mandie M(or H, depending if i use my birth or adopted name lol).

But, I can try to explain this to you!

We used to have the same thing. Every spring rain they were everywhere. In fact, we used to stage "save the frogs" rescues at the main intersection in our village - I remember there being at least 50 kids at a time at points, stopping the cars to save the frogs. Luckily because this is such a small town, it was just accepted, and people were very patient about it, and I can even remember police cars being parked nearby to help with the safety of said rescues so that the kids were not stopping cars on their own. If someone was in a truly big hurry, there was a short detour that only took about an extra 30 seconds to drive so I think thats why it was so easily accepted. We would often make signs and everything and the kids would collect all of the toads in the intersection and then let the cars come through. There is a swampy area right beside the intersection, and I suspect thats why we found so many right in that area. I am sure lots of poor toadies were dying in other roads in the village but we focused on the intersection.

The type of frog you are thinking of could be of several varieties, and could in fact, be a frog OR a toad. What state are you located in? This will help me narrow down what you have locally and I can probably point you in the direction of photos of it so you can make an educated guess. Without being there though theres really no way for me to identify, as this phenomenon happens with alot of species, and not even just frogs!

Here is what Wikipedia has on the subject:

I will be back with more info, Im installing a new program and it needs me to close my browser. Take a look at that for now!