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The ladies behind the National Womens History Museum have been fighting for 15 years to get an appropriate commemoration of women near the National Mall, and today marked a milestone of sorts: The second introduction of legislation that would authorize the sale of a chunk of land on 11th Street south of Independence Avenue for “fair market value,” to be paid for with private donations.

How egalitarian! Even…womanly!

“They say that women are more fiscally responsible when it comes to handling the family checkbook,” said Rep. Judy Biggert at a press conference today. “This proves the same is true for the national budget!”

The problem is, the “fair market value” has no dollar amount right now, because the NWHM organizers don’t know exactly what piece of land they want.

Biggert threw out one figure: $50 to $60 million. But when I asked NWHM president Joan Wages about that, she vigorously denied that any such figure existed, because no independent assessment had been conducted. Of course, if the fair market value is known before the legislation passes, they might have a lot harder time raising the money (they’ve got $10 million in the bank so far, and another $10 million in pledges contingent on acquisition of the site). “You’re about to cost us an extra $50 million dollars!” Wages fretted.

Currently, the land addressed in the legislation is owned by the General Services Administration, so it isn’t taxed. But it is assessed. The legislation defines the property as “generally consisting of Squares 325 and 326,” and the 2012 assessments for those lots add up to $51,096,770, which probably explains where Biggert got her number.

But the legislation also defines the property as “generally bounded by 12th Street, Independence Avenue, C Street, and the James Forrestal Building,” currently a parking lot, which is valued at only $2.8 million. The rest of the land—Square 326—would cost a lot more, because it also contains an Agriculture Department building called the Cotton Annex. NWHM might want that building for their 200,000-square foot facility, but they’re not sure yet, hence the ambiguity.

“There may be a point at which we say well, we do need some of that land in parcel 326 to make this work,” Wages said, when I called her back. “I think that’s why its written like this, to give us a little bit of flexibility.”

She said she tried to get her lawyers, GSA, and the House and Senate Committees to better define the legislation, to no avail. So if it does come to a vote, legislators won’t know what piece of land they’re telling GSA to sell off. Not that they’ll likely care that much, of course. But the Department of Agriculture might.