Thats the number from an advertisement on the side of a bus, for some missing children organization, back in 2001. It stuck to me.
I just found some numbers from 1988
354,000 family abductions a year
3,200 to 4,600 stranger abductions
450,000 runaways.
in 2002 another study came out.
According to NISMART-2 research, which studied the year 1999,
an estimated 797,500 children were reported missing;
58,200 children were abducted by nonfamily members;
115 children were the victims of the most serious, long-term nonfamily abductions called "stereotypical kidnappings"; and
203,900 children were the victims of family abductions.
Seems there is several hundred thousand kids no accounted for in that quote.
This sheds some light
An estimated 203,900 children were victims of a family abduction in 1999. Among these, 117,200 were missing from their caretakers, and, of
these, an estimated 56,500 were reported to authorities for assistance in locating the children.
Forty-three percent of the children who were victims of family abduction were not considered missing by their caretakers because the caretakers knew
the children’s whereabouts or were not alarmed by the circumstances (see “Conceptualizing the Problem,”).
Forty-four percent of family abducted children were younger than age 6.
Fifty-three percent of family abducted children were abducted by their biological father, and 25 percent were abducted by their biological mother.
Forty-six percent of family abducted children were gone less than 1 week, and 21 percent were gone 1 month or more.
Only 6 percent of children abducted by a family member had not yet returned at the time of the survey interview.
In Vegas. 
