Interesting. I did my research via Amazon, and they list it as a trilogy by Cormac.
2 suggestions. The 1st is Cormac McCarthy's border trilogy. Yeah I know you didn't want a series, but I thought I might suggest it since its available in a collected volume.
Also worth reading would be Don DeLillo's Underworld. A bit overlong maybe, but it's best moments are exceptional.
https://www.amazon.in/dp/0375407936/ref=cm_sw_r_cp_apa_i_UuPZzb6X2HT65
Don't know if Amazon links are allowed or not
The Border Trilogy: All the Pretty Horses, the Crossing, Cities of the Plain (Everyman's Library) https://www.amazon.com/dp/0375407936/ref=cm_sw_r_apan_i_V5J5AK36J103GW29TX21