My experience has been the opposite. During college, I had an internship at a defense contractor and I was the only Asian intern there (out of maybe 20 people). There were a couple of black guys and the rest were caucasian. IME, people of color had the hardest time obtaining a clearance. It took around 2.5 years for me and around 2 years for one of my black coworkers. The turnaround time for the white guys was a lot smaller.
I think this experience was for the best though - I left shortly afterward, because I won't stay where I'm not wanted.
Like, if I apply for a job in Nigeria that needs clearances, if the other guys are all from Nigeria then investigating their backgrounds are consistent, talking to their neighbours, etc., is relatively easy. Especially if they all have parents who already have files with identity info.
If I'm from Kenya, then first up you're going to need translators, then you're going to need political accord or covert operatives, birth records in rural Kenya possibly don't exist.
Also you want to leave me for a while on observation to see if I do anything suspicious; that needs time.
It doesn't matter if the Nigerians want me, to do the same level of investigation would take far longer.
Why do you assume that non-white people are not "3rd/4th generation natives"? Black people have been in America since before the country even existed, whereas my own (white Italian) lineage has been here less than a hundred years.
The GP stated they were Asian, so presumably they at least have less establishment in USA than a person from USA.
Perhaps they meant their family at some point in the past came from Asia, but if they couldn't describe their heritage clearly that wouldn't really be my fault.
Asian is just used as a description of someone's race in the US. It doesn't imply that a person was not born there. The OP also mentioned black coworkers without saying anything to indicate that they were not from the US.
Does that not seem reasonable?
And for some clearances not having all four grandparents be natives is a big hurdle - it certainly use to be that way in the uk civil service when I started work
I'm not sure what the correct term would be though. "Natural born citizen" normally means someone who is a citizen through birthright, usually, but not always, because they were born within the US.
The phrase that I've most commonly heard is "Nth generation American", but does this require all members of N generations to be citizens? My daughter is eligible to be a "Daughter of the Revolution", but I'm not (yet) a citizen
Obviously there can be reasons in specific cases, but there should be no reason why it takes longer in general. At least, no reason that I can see. What are you thinking of?
It is no doubt overly simplistic to assume conscious racism, but as this thread demonstrates, Americans who are not KKK racists nonetheless have a lot of subconscious attitudes regarding race that can have an influence.
[0]: http://web.stanford.edu/~learnest/les/mongrel.htm