Amazon has offered free shipping to US customers for over a decade now on all eligible orders above $25, but that's changing today as the online retailer bumps up its minimum order requirement to $35. Amazon notes that this is the first time it's increased the order requirement for its "Free Super Saver Shipping" option in more than 10 years, and that members of the $79 per year Prime service will still receive free shipping on all orders. While Amazon doesn't detail why it chose to increase the order minimum, the decision could be a matter of increased shipping costs and an interest in positioning its Prime service as a more attractive option. Now that buyers will need an even bigger order to get free shipping, it's possible that Prime's promise of no minimum for no-charge, quick delivery will be all the more enticing.