With estimates in the tens of thousands, immigrants and their supporters took to the Mall yesterday in a massive show of force in favor of progressive immigration reform. As the Post notes, quite a few of the marchers were taking their first steps into political activism, a step that is having a noticeable impact on Capitol Hill. Area bloggers have started sending us their experiences from the march, so if you have any to share, post them in the comments section. We also have plenty of pictures popping up in our Flickr photostream. Of course, that many people made for quite the commute home for areas workers. Pedestrian Scott Travis was quoted in the Post as saying, “I looked up and saw the protest going on…I then looked up the route and decided, ‘Uh-oh, time to bail.'” Good move, Scott.

Williams Waffles on New Hospital: Plans for a new $400 million hospital on the eastern fringe of Capitol Hill in Southeast seem to be coming upon hard times in regards to supporters. NBC 4 is reporting that D.C. Mayor Anthony Williams, once an ardent hospital proponent, has pulled his support for the project. As quoted in the Examiner, Ward 6 Council-member Sharon Ambrose, who represents those in the neighborhood where the hospital would be built, says the mayor is “coming to grips with the political and financial realities” of such a large-scale project.

Nationals Home Opener Tonight This Afternoon: With Vice President Dick Cheney set to throw out the first pitch, the Washington Nationals will have their first home game of the season today, writes NBC 4. They’ll be playing the New York Mets, and according to news reports, as of Monday afternoon there were still around 9,000 tickets available for the game. Can we call it the Cheney Effect?

Parking Lots Full at Reagan: Taking Metro to the District’s closest airport is looking like a better and better idea. NBC 4 reports that due to increases in travel this season the airport’s parking lots are at capacity, Airport officials are suggesting that you call their 24-hour number, (703) 417-PARK, for updated parking information.

Briefly Noted: D.C. Police Commander gets anti-terror post … Hearing in Arlington continues on whether Wal-Mart should get in the banking game … Va. Gov. Tim Kaine signs bill to help with back-to-school costs … Battle emerges over church bells in Reston.

This Day in DCist: Martin talked about labor issues at the Post, and we grinned in blogging-form over the then-new Nats.

Picture snapped by maxedaperture.