Lenny asked for statistics on interbreeding (as opposed to just intermarriage/dating). Based on my analysis of the 2005 Natality Detail File :
Of 2280259 children born to Non-Hispanic White women, the racial breakdown of fathers is roughly:
89.23% Non-Hispanic White
3.18% Non-Hispanic Black
2.13% Non-Hispanic Other Races
Of approximately 2217946 children fathered by Non-Hispanic White men, the racial breakdown of mothers is around:
92.76% Non-Hispanic White
0.96% Non-Hispanic Black
2.17% Non-Hispanic Other Races
These numbers are not inconsistent with the facts in my previous post: lower-quality women, who are more likely to engage in miscegenation, also unfortunately account for a disproportionate share of births .
For white mothers with Bachelor's degrees or above, the father is white in 94+% of cases. For married white mothers, the father is white 93% of the time. The educational breakdown of white mothers of white children vs. white mothers of mulatto children:
Less than HS: 9.1% vs. 19%
HS grad. or GED: 23.5% vs. 35.5%
Some college: 21.1% vs. 24.6%
Associate degree: 9.6% vs. 7.2%
Bachelor's degree or above: 36.3% vs. 13.1%
Education levels of white women who breed with Hispanics are similar to those of white women who mate with blacks.
So, on a positive note, while interbreeding will contribute to a reduction in the number of whites in America, it may slow the dysgenic decline of the whites who remain.
 "The public-use Natality Detail Files include all births occurring within the United States. Births occurring to United States citizens outside the United States are not part of these files. Data are obtained from certificates filed for births occurring in each state."
2005 is the most recent year for which this data is available. Race of father is "unknown or unstated" for about 9.6% of births to white mothers (the fraction is larger for most other groups). In the overwhelming majority of cases, when the race of the father is unknown or unstated, the mother is unmarried. My estimates assume the racial breakdown of fathers in these cases follows that for unmarried mothers of a given race where race of father is reported. Since about 10% of white mothers where the race of the father is not reported are married, and because I have ignored the (small number of) mothers with race unknown or unstated, the numbers I post above probably slightly overstate rates of interbreeding for white women and understate numbers for white men.
In a 1988 study, Retherford and Sewell examined the association between the measured intelligence and fertility of over 9,000 high school graduates in Wisconsin in 1957, and confirmed the inverse relationship between IQ and fertility for both sexes, but much more so for females.Also likely contributing to the lower interbreeding rate by white men: the U.S. Hispanic population contains significantly fewer females than males.
In a 1999 study Richard Lynn examined the relationship between the intelligence of adults aged 40 and above and their numbers of children and their siblings. Data were collected from the 1994 National Opinion Research Center survey among a representative sample of 2992 English-speaking individuals aged 18 years. Findings revealed that weak negative correlations of -0.05 and -0.09, respectively were found. Further analysis showed that the negative correlation was present only in females.
# Sex Ratio (Males per 100 Females) in 2000
* Latino Foreign-Born (113)/Native-Born (100)
* Mex. Foreign-Born (126)/Native-Born (102)
* U.S. Population (96)
* U.S. Non-Latino White (96)