It would be funny if your estimate is right. More people turn out for Mardi Gras every year in New Orleans!
My estimate is 50,000 to 75,000 in each clump. I’ve been to events on the West Lawn of the Capitol several times over the years, and that crowd in the photo looks like the 60,000 to 80,000 I’ve heard bandied about in the past.
So multiplying that by the 9 or r 10 “clumps” I’d guess (emphasize guess!) there were 500,000 to 750,000 in attendance. Not the 1.5 million they’ve been tossing about on the TV news here in DC Metro.
From the DC Metrorail web site (and as Charles Wayne notes above 973,000 “trips” = about 486,500 round-trip riders):
http://www.wmata.com/about_metro/news/PressReleaseDetail.cfm?ReleaseID=2439
As of 7 p.m. 973,285 Metrorail trips on Tuesday, January 20
Even before the day had ended, Metro set ridership records on Inauguration Day.
People took 973,285 trips as of 7 p.m. The figure breaks the all time rail ridership record of 866,681, which was set yesterday.
[snip]
Metrorail’s Top 20 Weekday Ridership Days
Date Ridership Event
1 01-20-09 973,285 (as of 7 p.m.) Obama Inauguration
2 01-19-09 866,681 Obama inaugural events
3 07-11-08 854,638 Baseball/Women of Faith Conference
4 06-09-04 850,636 Reagan State Funeral
5 06-25-08 846,388 Smithsonian Folklife Festival/Baseball
6 07-10-08 844,530 Baseball
7 07-08-08 835,072 Baseball/Basketball
8 07-02-08 834,956 Smithsonian Folklife Festival
9 04-03-07 831,508 Cherry Blossoms/Baseball
10 06-24-08 831,464 Baseball/Basketball
11 06-20-08 829,998 Baseball/Basketball
12 04-24-08 828,973 Baseball/Basketball
13 04-17-08 828,418 Pope Visit/Soccer
14 04-11-08 828,132 Baseball/Cherry Blossoms
15 06-27-08 825,862 Smithsonian Folklife Festival/Baseball
16 06-18-08 823,516 No Event
17 07-01-08 822,931 No Event
18 04-10-06 821,283 Immigrant Rights Rally
19 06-19-08 819,979 No Event
20 06-26-08 819,722 Smithsonian Folklife Festival