Good for you Looking for checking out the data.  If you've found the current population you know California is some 8% black, Washington 5% and Oregon 3%.  Cal is at about three million, Wash about a third of a million, and us just over 116,000.  Way up from 128  (0.24%) in 1860!

You ask: how did those blacks get here earlier  if it was against the law?   Good  question. The answer, the law was only casually enforced.  The law impacted but did not eliminate "free Negroes" coming here.  (think of our earlier Marijuana laws) Only Jacob Vanderpool was evicted while George Bush chose to move to Wash to be free of such laws..

As Nokes notes in "Breaking Chains"  (good book you should read ) there were up to 50 slaves in Oregon, again in spite  of the anti-slavery laws.  Regarding the exclusion laws he states "But while the exclusion laws were rarely enforced in Oregon, the tragic legacy of the laws  was that they discouraged blacks  from coming at all. (p 171)