Walter Brennan is in it?
The setting is west of the sun.
Lee Van Cleef is in it?
What makes a movie a Western? The much greater risk of stepping into a cow-pie.
I think the 3 primary identifiers of Westerns are the wardrobe (cowboy hats, boots, chaps, or other clothing that evokes the wild west in some way), the set design (must be dusty and, if in color, sort of tan), and the score (must include some combination of fiddle, ocarina, acoustic guitar, tuba, and/or jaw harp).
This is a western.
Needs more sousaphone.
Marion Robert Morrison is in it?
Westerns are narratives of the frontier.
Needs more dust, but…
Late to the party.
What makes something a “Western”?
You can argue that location and dates it takes places was the original metric of what a Western was: in the past, in the “west”. The “West” would be anything west of the Mississippi. It was both an aesthetic and a combination of tropes.
I think the definition can expand a bit to include modern or “space westerns”. I think the main thing that is required for that is: areas that are unknown, unsettled or lightly settled, and without any overarching centralized authority to keep the peace.
You get a setting like that and it is ripe for people be taken advantage of or oppressed, and others who are fighting that oppression. Or taking advantage of the chaos to make a living one way or another. They have the freedom to move about and do what they want, but there is also the danger than someone will cross their paths and harm them.
Finally, re the 2nd comment, I haven’t seen Killers of the Flower Moon yet to be able to speak on if I feel it is a Western or not. The trailer read to me more of a crime drama, but I imagine there is a case to be made, even if it is a bit of an outlier.
Oklahoma for the longest time was a roped off area to sequester the Indians and not considered anything but an open air prison. Today I would consider it part of the Southwest, but because of it’s location and demographics, it blends with the Midwest, the Ozarks, and Texas. Historically, though, they ran the cattle trails up through it and definitely a setting for a good Western. The High Plains even goes through the Oklahoma Panhandle.
Pierre Louis Baron le Bris is in it?
No, that’s a Dick Francis novel.
James Garner is in it?
Jack Elam is in it?
Now the way this story ends… is that they get married and he goes on to become governor of the state. Never gets to Australia, but he keeps readin’ a lot of books about it. I get to be sheriff of this town… and then I go on to become one of the most beloved characters in Western folklore.