Well, simply by looking at the memoir of Solomon Northrup, "12 Years a Slave", written in 1853, it's easy to see that, yes, there were everyday friendly interactions between African Americans and white people in that time period. This is also depicted in the film based on the memoirs. Northrup writes that he was respected in New York for his violin playing skills. He even owned land. After he became a slave he still mentions positive interactions with certain white people. He described William Ford, his initial owner, as a "kind, noble, candid Christian man". Northrup was even eventually freed thanks to a white Canadian. I realize that this is simply one example of one man. But it proves that your friend's thought that it's "virtually impossible to believe that white and black individuals could befriend each other in that time" is false.

Your roommate's view, that NO ONE could be friends, is absolutely wrong. I'm going to approach my response via interracial marriage, but I'd also like to note that in states like Massachusetts, there were both black and white activists spending years demonstrating (successfully) to integrate public schools in the 1840s (Boston's school system was integrated in 1855), thousands of schoolchildren over the years studying, eating, growing up together. I can't speak to other states' education systems (I live in MA.)

But, on to interracial marriage— I think marriage counts as a a friendly interaction, no? I'm gonna quote from an article, BLACK/WHITE INTERRACIAL MARRIAGE TRENDS, 1850–-2000 Gullickson 2006, Journal of Family History. From the first paragraph of his conclusion:

Interracial marriages were uncommon, but not necessarily rare, prior to the end of Reconstruction. While the increase in the size of the free black population due to emancipation reduced the visibility of interracial marriage among blacks, declines in the underlying propensity to intermarry occurred only after the end of Reconstruction. White policing of the color line in the South and “latent” racism in the non-South contributed to a drastic overall decline in both the odds ratio and the outmarriage ratio between 1880 and 1930, although there may have been an upward spike between 1900 and 1910. This decline was delayed in the non-South until black migration out of the South increased the relative size of the black population after 1910. With the atrophy of the Jim Crow state after 1930, the frequency of interracial marriage increased briefly before stabilizing in the civil rights period. With the twilight of the civil rights era, the frequency of the interracial marriage began to increase at a steady exponential rate. This growth began after 1960 in the non-South and after 1970 in the South.

Interracial relations, though not necessarily marriages, were also common in the colonies in the 17th/early 18th centuries, before the system of racial discrimination had become firmly enshrined. This quote is the view of historians, not from his analysis of census data, but I'll include it:

Interracial sexual contact likely peaked sometime during the early colonial period, when white indentured servants and black slaves were in close contact in large numbers. The practice of keeping white indentured servants was on the decline and African slavery was on the rise, leading to a transitional period in which the two groups often lived and worked in close quarters. This interracial exposure at a time when folk ideologies of racial difference were still in their infancy probably produced the highest level of interracial sexual contact ever observed in this country. As Edmund S. Morgan notes, “It was common, for example, for servants and slaves to run away together, steal hogs together, get drunk together. It was not uncommon for them to make love together.”2

The rise of interracial sex led white elites to create antimiscegenation statutes in an effort to define boundaries between white servants and black slaves, whom slaveowners feared might band together in open rebellion. The children from such unions also posed a potential problem for the emerging racial system as elites grappled with a classification of people that would reinforce the institution of slavery. Efforts to reduce the level of interracial sex were assisted by a decline in the practice of white indentured servanthood, which increased the segregation of black slaves from white laborers.3

For the data analysis, he looks at married households, here using random census samples of 1% of the free population (so, enslaved african americans excluded, this is only looking at freedmen and women) provided by the University of Minnesota, and tries to restrict it by disregarding couples over 30 or over 40, who probably got married in previous decades. Here's the data he was working from.

At a glance, you could extrapolate that in 1860, before the Civil War, there were ~1600 free interracial married couples living together where the man was between the ages of 20 and 40. Obviously that's still a tiny minority out of the total 2401700 free married couples between 20 and 40, but free African Americans were of course already a minority to begin with. And it's absolutely not 0. By 1880, a prime setting for Western movies, you could find almost 4000 interracial unions between the ages of 20 and 40. And this is only married couples living together on the census, not just people who had a friendly relationship briefly.

Outside of this chart, he also has graphs comparing rates for the North and South and analysis of the differences, if you want to read around page 302.

Sorry to dogpile, but I never got an answer to this questions and it's sort of related, so I thought I'd throw it up here:

In "What Hath God Wrought" by Daniel Walker Howe, he writes that there were biracial Methodist services.

By 1820, one Methodist in five was black, and the percentage of black Baptists was probably even higher. In the South, most congregations held biracial services, with blacks and whites usually seated separately. Members of the two races heard each other's preaching and caught each other's forms of prayer and praise. Howe. "What Hath God Wrought" p. 198

It seems a little odd to picture white antebellum southerners seated in a church listening to a black preacher. Separate rooms maybe? Does anyone have more information about how this might have worked?

California was not a "slave state" but it was hard on its black population. It passed laws that protected slave owners and also laws that prevented Negros from giving evidence against a white person in court.

The members of the Zion Methodist Episcopal Church from San Francisco sent 65 people to Vancouver Island and were welcomed by Governor James Douglas. There they were told that after 7 years residence they would become British subjects and enjoy the same rights as all of Queen Victoria's subjects. Around 400 immigrants came to Vancouver Island and settled soon after.

Governor Douglas appointed some to the Victoria police department, but recalled them soon after. Not because of any wrong doing on their part but for their protection instead. The city was receiving a large influx of American gold miners heading to the Fraser River gold rush and these miners were causing much grief for the Negro policemen.

In 1860 a slave named Charles ran away from his owner, Major James Tilton from Olympia, Washington Territory. Charles heard that slavery was not allowed in British lands so he stowed away on the Eliza Anderson, an American ship.

He was caught on board and locked up in a cabin to be returned to his owner. When the Negro community heard this they went to the police who then went to the ship to release him. The police managed to have Charles turned over to their custody to have a hearing as to whether Charles was legally imprisoned. Then once they had the slave on British land declared that slavery was repugnant to the British law so a slave became a free man once he stepped on British soil.

Source: BC Chronicals by George and Helen Akrigg

Edit: Here is a more complete version of Charles release.

Mark Twain or Samuel Clemens was one white man who was friendly to black people, enjoyed their company and had a positive opinion of black people in spite of being raised in the racist South.

If you read Huckleberry Finn with your eyes open you will soon notice that Jim is the only decent human being in the whole book. Huck is just a boy, his heart is all right but he makes foolish mistakes. Everyone else is flawed, from Huck's pappy, a mean drunken racist, to other people who are foolish, or cowardly, or dishonest in some way.

Clemens himself struggled with the race question all his life, but every time he mentions black people in his books it is in a positive light.

He described Huckleberry Finn as an effort to create a true picture of the people he knew on the Mississippi in his youth before the war, a world that was dying or dead when he wrote the book in the 1870s.

There are many examples of black and white working together, not so much socializing together. You will notice that black and white mix together at public gatherings where everyone is standing up but the don't sit down together to eat or drink at least in the south.

If you look at Frederick Douglass' autobiography, he talks about friendly interactions with whites throughout the book (which was designed as an anti slavery tract). In an urban setting, he talks about playing with young white boys in his free time and bemoaning to them that they were free and would grow up to be free while he would be forever a slave.

I also think the book also importantly shows how slaves had some freedom, but the freedoms they had were turned against them. He talks about how slaves used money they made or acquired to hold celebrations between Christmas and New year's, and that the slave owners encouraged the slaves to use their time off in drunken revels rather than anything productive. Douglass saw this as critical to maintaining the whole system of slavery, without the release of holiday slaves could not have been kept down, and it burned off any accumulated surplus they might manage.

Well....according to my family tree my great great grandfather had 6 children with a white woman (not mulatto) before the civil war. I also have a great great grandma from Norway (stories passed down claim she was very tall and very blonde) who legally married a black man in North Carolina in 1872. I don't know the specific laws at the time but I have a marriage certificate as proof. I also have a will from a man who owned a family member of mine and he left him not only his freedom but a mule, 2$, a wagon and some other stuff....more than he left his own children and wife.....My guess is that most of these people in my family and probably most of the South worked/lived on the same farm or mill. I also find in my research that poor white southerners who worked as share croppers and/or indentured servants mingled with the african americans. Most grew up together and remained in the same towns/cities for generations....maybe people just don't want that part of our history to be known.