to span

[Isotope]

Hi everbody!

I just need some help clarifying the meaning of that sentence:

"The material in this book has been compiled from interviews spanning over 30 years and myriad sources."

I'm not sure what "to span" means here. I'm pretty sure it doesn't mean that the interviews took as long as 30 years before they were over

Thanks for your help!

[SoothingDave]

The interviews took place over 30 years. One interview might be from 30 years ago, another from last year and all times in between. They span the 30 years in the same way a bridge spans a valley.