If you're one of the many joining, there's a lot you'll want (and need) to know, from travel logistics to security measurements — that, of course, includes being smart about the bags you're carrying, and what you're intending to pack. Naturally, with a national demonstration of this scale, organizers have noted that security will be strict; according to the March's official site , "all backpacks and bags may be subject to search at the March, and those not conforming to the standards set here may be confiscated or asked to be left behind. Backpacks are not permitted unless they are clear and no larger than 17"x12"x6" (colored transparent bags are not permitted)." So, you can bring a bag, but it has to be small and clear — which definitely isn't the easiest combination to find.