By Thursday afternoon, workers had run the new fencing all the way down to, and along Constitution Avenue, which crosses in between the White House and the Washington Monument.
The move to close off the Ellipse - an over 80 acre park which often hosts families, tourists, joggers, and picknickers - was reminiscent of other moves by the federal government to increase security, without the consent of the Washington, D.C. government.
For example, after the Oklahoma City bombing, Pennsylvania Avenue in front of the White House was closed to traffic.
Roads were also closed to through traffic on Capitol Hill near House and Senate office buildings, and security bollards were placed in front of a number of federal buildings, museums, and monuments.
Because the federal government controls many of those areas, they are not under the direct jurisdiction of the District of Columbia.
"I'm also concerned that some of the hardening that they are doing may be not just temporary," the Mayor said of the new security fencing.
Extra fencing has already been put in place to the north of the White House, to wall off Lafayette Square from demonstrators.
Here's a satellite map of the area around the White House to give you a better idea of the changes which are being made:
The red area at the top is Lafayette Square. This is normally open to the public, but now a tall fence at the northern end along H Street does not allow anyone into the park.
The yellow area is the normal White House security perimeter. The Old Executive Office Building is on the left, and the Treasury Department is on the right.
The orange area at the bottom is how the perimeter is being extended with new fencing to add in the Ellipse, which is normally open to the public.
The road at the bottom of the graphic is Constitution Avenue.