Where It All Goes Down
The Suburbs of Sydney, Australia, Present Day
Here's the thing about Sydney: The place is huge. With a population of over four million, the area surrounding the city is made up of six hundred and fifty suburbs. Having said that, let's think about our story.
We know that Lonnie lives in Toongabbie, an industrial community about eighteen miles west of central Sydney, and that Pop and Nan live in Katoomba, a town in the Blue Mountains on the outskirts of the city. While we don't know the names of the suburbs Lily and Clara live in, we do know that they live at stops along the Sydney rail line.
So while all our characters may live in the same community, they're spread out in different parts of it. Clarke's narration shows this by giving us a panoramic view of what the characters are doing across the story's geography. Check out the beginning of Chapter 4 as an example: We see how "the winter night […] crept down from the mountains where Nan and Pop lived" and how "Lights came on in the streets and houses, in Lily and Marigold's place and in Lonnie's Boarding House for Gentlemen" (4.1). It's a bit of a bird's-eye view of the location.
More importantly, the geographical gaps between the characters reflect the many rifts between them in terms of generation, marriages, career choices, parental expectations, and yes, even ax incidents.
One Whole and Perfect Day is largely about these characters finding ways to move closer to each other and abandon their prejudices and grudges from the past. Clara attempts to separate herself from her parents' dysfunctional relationship, Lonnie tries to discover who he is independent of his family, Lily wants to bridge the gap between herself and other people her age, Pop must confront his disconnection with modern culture. The list goes on. And as it does, characters spend time either farther apart or closer together geographically.
Another key element of Sydney as a setting is the diversity of the community, which plays a huge role in the conflict of Clara and Lonnie's interracial relationship. Here's the short version (you can read the long version here): In the 1850s, Chinese people immigrated to Australia in the hopes of striking it rich. The supply of gold wasn't endless, though, and when it ran out, many immigrants chose to stay and make lives there. In 1901, though, the government passed the Immigrant Restriction Act, which significantly lowered immigration until it was lifted in the 1970s.
So how does this element affect the characters? Stan would have grown up in a time when the IRA was still in place and had a huge influence over the locals' views of foreigners. By contrast, Lily, Lonnie, and Clara have been raised in a multicultural society where Chinese people are part of the community. This racial component of Australian culture is another element that significantly divides the characters from each other.