A couple of things, one a trimester is 14 week. And here are some statistics you may find interesting.
From Planned Parenthood site
Between 1990 and 1997, the number of abortions in the United States fell from 1,429,577 to 1,186,039 (CDC, 2000). The CDC estimates that 55 percent of legal abortions occur within the first eight weeks of gestation, and 88 percent are performed within the first 12 weeks. Only 1.4 percent occur after 20 weeks (CDC, 2000).
As far as I know NO state allows for 2nd trimester abortions on demand, there are criteria which need to be met ( mother's health, rape, incest etc.) and those limits become even more restrictive after the 20th week.