Hello yes, when adding the discount you'd set Discount Applies To: Cart Item Total and enter 50STATES
in the Discount Code field. This discount would then be applicable to any purchase, regardless of the item(s) purchased.
However, if you have other products and only want your 50-state ebooks to be eligible for this discount, you'd need to set Discount Applies To: Item Unit Price and select an applicable ebook product, add the discount, then repeat this for each other applicable ebook product.