WHERE WILL WE ALL STAND?

If people in a crowd are not tightly jammed together, it is reasonable to suppose that each person will occupy roughly 4 square feet.  200,000 people will occupy 800,000 square feet.  There are 43,560 square feet in an acre, so 200,000 people in a crowd, with no open spaces here and there will occupy somewhat more than 18 acres.  Realistically, a crowd of that size will certainly occupy 20 acres or more.  The march on Saturday is gathering at the southeast corner of the Washington Mall.  The Mall, from the Capitol to the Washington Monument, is 106 acres, but much of that is occupied by the rows of trees on each side.  The open area, that long green space reaching from the Capitol to the Monument, is, by my calculation, about 1.8 million square feet, or 41.3 acres, which suggests that the march participants will fill half that space.  Can that possibly be right?