Yeah, I remember the migration to Tulsa being discussed. I'm sure there will be black communities in the north, but I don't think you'd see anything like the large black urban communities which developed in almost every northern industrial city IOTL.
That actually makes me wonder about how common the existence of "sundown towns" are ITTL.
I read an excellent book on it some years back. Basically following the Civil War, blacks moved to the north, but mostly did not move to urban areas. They moved to rural areas and/or small towns, since they were from rural areas to begin with, and that was where they felt most comfortable. Most every rural town in the lower Midwest had a few black families. But as the "racial nadir" gained steam in the late 19th/early 20th century, they were systematically expelled from these small towns, until they ended up forced into black neighborhoods in major cities, only to later be drowned out/forgotten following the Great Migration. It was basically the same historical pattern that forced the Chinese into Chinatowns.
ITTL, things didn't get quite as bad in the north regarding racism. I think it's been established the Exodusters were more successful, for example. So I would presume many small towns in the north retain minor black populations. Of course, this is not going to be stable indefinitely - presuming they've now lived up north for 80 years. Many communities have likely died out through attrition or intermarriage, but it's probably not considered unusual across most of the U.S. by this time to have a black family or two in your community....
I think to say that racism is "not as bad" in the North ITTL is not at all to say that a generic average representative Northerner has somewhat more moderate views; it is more to say that the argument between hard-line racists and people with a more inclusive vision has not been silenced by the sweeping triumph of the former. I would guess that as you say, the initial phase of the southern blacks settling here and there in the north went as OTL. But then, the factions and movements that dampened what enthusiasm there was among Northerners for the welfare of African-Americans had more mixed success. OTL and presumably here, abolitionism before the Civil War had considerable traction in the north, especially the old Northwest aka "Midwest" today--but motives were mixed. Some had high-flown moral reasons, others merely saw slaveowners as dangerous competition for free labor and free-soiler settlement opportunities in the West. Few however knew any African-Americans; many western settlers hoped to opt out of the whole slavery/abolition issue by simply forbidding African-descended people from settling in their territories at all.
The Civil War changed things though; some white northerners resented the freed slaves and the abolitionists for stirring up trouble that cost them so much, but others, who had the experience of leading black soldiers or seeing slavery up close and then seeing what it meant to its primary victims to see it abolished at last, came to appreciate African-Americans as people and fellow citizens all the more.
ITTL, I suspect the legacy of South Carolina's self-liberation, and a bit paradoxically Lincoln finishing his second term and the absence of the imposition of sweeping Reconstruction from above by the Radical Republicans all have the effect of strengthening the position of pro-Africanism among white people. The SC example should be self-explanatory; Lincoln's avoidance of radicalism, which implies conservative Southern interests quickly regaining control of most of the South, deprives the mythmakers of the unified American White Race of much of their favorite OTL material; it is much less easy in this timeline for the Southern states to construct the myths of the glories of the antebellum days and the magnificent Lost Cause. Union armies are not kept mobilized to enforce Reconstruction for a decade--so there will be less disenchantment with the
Northern noble cause.
This is a general thing, but in the spirit of much of the other conversation here recently, I think it will have play due to the greater relevance of locality ITTL. That is, I suppose that despite the factors above, racism based on the solidarity of the "white race" against others will indeed gain currency here and there--but not quite
everywhere. In some of those Midwestern and northwestern settlements where southern African-Americans migrated to, they will be cast out as per OTL, but in others, they will integrate more strongly into their communities--and in still others, maybe only a few, some of the outcasts of the more intolerant towns will be welcomed in by both white and black locals. I suppose that instead of all of them going to urban ghettoes, there might arise some largely-black rural towns, and many others where they are respected community members.
These towns might not, I fear probably won't, be a majority of the towns nor hold a majority of any state's residents. But the point here is, the pro-African argument, uttered by both white and black voices, will not go silent. The Redeemers and Klansmen and their ilk will be able to attempt to rewrite history as per OTL, but not everyone will forget that these are lies.
Now on the other hand you mention that the African element of many of these towns would be forgotten through, among other things, intermarriage. I suspect that intermarriage will happen, but I don't think ITTL that the "One Drop Rule" of OTL USA will be swept away. If someone in one of these more welcoming towns (and cities, why not?) is known to be descended, even only distantly and in a small degree, from someone African, then they will be seen as "black." Intermarriage will not dilute the perception of African presence, it will inflate it!
The difference would be, in some of these towns, and hence to a small degree everywhere in the nation, being black will be more respectable. That is to say, in some of them it would be quite respectable (at least, being seen as one of "our black folk" as opposed to more dubious outsiders). Something approximating actual social equality might evolve here and there--but I don't think Americans will stop seeing racial distinctions. They just might stop fearing them.
And elsewhere, they won't stop fearing, not at all. We have seen Woodrow Wilson as a stand-in representative of white fear--and indeed, reading the latest installment about the Troubles of Alabama, I can understand his panic a lot better now!
Another factor at work is the lesser degree of ethnic homogenization we've been arguing about. The identity of being a "white" person in the OTL USA, particularly in the 20th century, is almost the opposite of a positive embrace of one's actual ancestors. The actual descendants of John Adams or other Revolutionary patriots might make something of that, but the vast majority of today's "white" people have no ancestors who were involved in the American Revolution, or even were on the wrong side of it (as Britons who had not yet emigrated, for instance!) Most can't even count as much as half their ancestry from Britain; as observed by another comment here and noted quite some time ago by demographic scholarship, the single largest European source of ancestry of "white" Americans is German.
OTL, to claim, and to be accepted as, a "white" American is mainly to disavow and forget the actual details of one's actual ancestry, or at any rate to prove to all challengers that one's Italianness, or Polish roots, or Swedish or Slovakian origins are all beside the point, that one is first of all a generic "American." And this proof is accomplished in large part by hatred and disavowal and proof of no ties to certain outsider groups--"foreigners" in general and African-Americans and Indians in particular. (Unless the Indians are effectively dead! If "the only good Indian is a dead Indian," as the OTL Western movies tended to assert, then dead Indians are good--claiming a bit of ancestry from some native people who are long gone, or at any rate made completely irrelevant as a distinct people, from one's own neighborhood adds a spicy cachet, and also is a way of claiming entitlement to the land.

)
All these factors and tendencies are still in play ITTL, but they are offset. In particular if the nation is more notably a patchwork of multiple local ethnicities, then American identity is much less a matter of claiming a curiously blended and homogenized but still distinct
racial identity, and more a matter of acceptance of the American revolutionary tradition, claiming to have answered the clarion call of the Spirit of '76 to all humanity and joined the ranks in terms of a voluntary compact.
In that light, there are few people more American in the United States than the African-Americans!

ITTL, more of them will be immigrants after the Civil War, and their specifically recent African or Caribbean origins will be more likely to be noticed and remembered, but still, most African-American ancestry will be from people who were here long before most "white" people came over, and that fact might be noted as relevant by more non-African people. Any questions about whether they have adopted the revolutionary compact would be settled by their role in the Civil War. More of the white friends and admirers they won in that conflict will remain allies. And the attempt to Other the Africans in the course of blending the diverse-origined "hyphenated Americans" into a forgetful white mass will be resisted by those who won't accept those terms for whiteness.
If the USA doesn't enter geopolitics as a partisan power, then the question of "who is aligned with the Enemy" does not arise, if no particular foreign power becomes a designated Foe.
Meanwhile, what opportunity American entrepreneurs do find overseas will be on the margins of empire, and in the gaps between them. African trade is both more lucrative and more important than OTL, and distinctly African-Americans are key players in tapping into it. Independent India opens up doors of opportunity--very distant ones, and to a people who don't have a lot wealth per capita--but there are lots of them! There aren't lots of Filipinos in comparison, but they too, and the self-liberating peoples of Indonesia, and the wavering allegiance of Zanzibar to Britain are more examples of places where small and distant opportunities beckon here and there; the best entree to such trade opportunities would be Americans familiar with the various cultures--but Americans of any hyphenated background at all can sell.