Two candidate explanations sit behind the crossroads pattern, and this atlas treats them as separate questions rather than one answer applying everywhere.
For Legba, Exu and Pomba Gira, a documented transmission history exists. Robert Farris Thompson's Flash of the Spirit traces the Fon and Kongo cosmological vocabulary that Vodun-descended and Kongo-descended communities carried across the Atlantic during the slave trade, arguing that the crossroads as a cosmogram, a point where the vertical axis linking the living and the dead crosses the horizontal axis of ordinary travel, is a specific inherited idea rather than a coincidence, reappearing in Haitian Vodou, Cuban Santeria, and Brazilian Candomble and Umbanda because those traditions share a documented West and Central African origin and a documented history of contact and exchange in the Americas afterward. Here diffusion is not a hypothesis needing to be argued from resemblance alone; it follows the same route the people who carried the belief are independently known to have traveled.
Hecate's crossroads cult has no such connection to the West African material and needs no such explanation. Ancient Greek sources place her at crossroads centuries before any contact between Greek and West African religious practice could plausibly explain the resemblance, and comparative religion has long noted that a threshold or a boundary drawing supernatural attention is one of the more independently recurring intuitions across unconnected cultures, without needing a shared source to produce it.
The crossroads pattern is therefore best read as two things that look alike: one transmitted along a known route the believers traveled, the other reached independently, with no such route to explain it.