Why do Infantry Soldiers still weigh 250-300 pounds saddled up and ready to go?

Great question. Let's say that a Soldier carries 100lbs of gear on their back. Not counting all of the other things (weapon, water, clothes, boots body armor, etc). Now, we make everything 50% lighter over the course of about 40 years. At the same time, we increase the size of the rucksack. Now a Soldier can still carry 100lbs, because that is what we have always done, right? So, we put more of the lighter weight material in there. We also add new weapon systems, new commo gear, new everything that didn't exist in the 70's. And...we come up with a load that weighs the same...we just carry more of it.

All the responses are pretty good but I will tell you that a lot of Soldiers carry more shit than they should. Not only Soldiers but leaders are just as guilty. Infantry guys are the worse because they fail to concentrate on planning logistics. It's all about the execution/actions on the objective when it's really not hard to coordinate for re-supply. Most operations these days do not require to RON, only occasionally will you spend more than three days outside a COP/FOB. Getting back into direct action operations are going to require more logistical planning to sustain continuous operations.

I can remember landing on or around an objective and spending three days living out of my butt pack. Rucksacks/supplies were slung in or trucked in after all pax and equipment landed. We have lost a lot of fieldcraft over the past 15 years. Leaders need to regain that knowledge and train their Soldiers.

If you assume the average person is about 5'8" and weighs 160lbs, then you ad:
8lbs clothes and boots
10lbs Sapi Plates (Side, Front, Back) & Helmet
7.5lb Rifle
15lbs Ammo (180 round = 30x 6 mags)

That's 200.5lbs before adding a pack.

Water weighs 8lb per gallon (Camelbak is 1/2 gallon, each canteen is 1 Qt)

It all adds up fast.