A look at Boston marathon tracking stats

A look at some of the online tracking and participant statistics from this year's Boston marathon:

Runners registered in the Athlete Alert program: 13,841, compared with 10,232 in 2006.

Number of e-mail addresses registered: 15,372, compared with 10,940 in 2006.

Number of mobile addresses registered: 22,091, compared with 16,201 in 2006.

Number of messages sent to e-mail addresses and mobile numbers: 192,354, compared with about 108,000 in 2006.

Race day visitors to marathon Web site: 1.8 million, compared with about 700,000 in 2006.

Number of 2007 Boston marathon registrants: 23,869.

Number of day-of-race starters: 20,640.

Number of finishers: 20,348.

Source: Boston Marathon.