A discussion with some parents led me to look into this, using the CDC's invaluable WISQARS application. I looked at accidental death dangers for young children, age 1 to 7, over the span 2001 to 2005; do not assume that this extrapolates well to older children, but run your own queries instead. Here are the results:
|Cause of accidental death||Rate per 100,000 children age 1 to 7|
|Car accident, child passenger in car||1.3 to 2.2|
|Hit by car while walking||1.3|
|Fire (not including house fire)||1.2|
|"Unintentional struck by or against"||0.1|
If you want to figure out the total numbers per year, multiply each number by 250 (since there are roughly 25 million children age 1 to 7 in the country). But the rate per 100,000 is of course more useful.