Though this is getting a bit ahead ourselves, looking at Mexico and Central America there are some good analogues to old-world areas.
Central Mexico is most similar to central spain but with volanoes and a possible theocracy ruled by the god-president of Mexico City. The Atlantic coast doesn't have a great analogue, the best one is probably Cuba, similar climates. This region along with Tabasco and Cuba are probably most similar to South-East Asia, Cambodia and Vietnam. Sinaloa is California but hotter. The southern Atlantic coast from Peurto Vallarta to Oaxaca is most similar to China's coast along Fujian and Zhejiang provinces, isolated and mountainous. The isthumus of Tehuantepec is probably the principle trade route between the Pacific and Atlantic It's populated along the entire route and there are good port cities at each end. Crossing further south requires large detours and dangerous travelling through jungles.
From Guatemala to Panama, this area is probably most like Indonesia. Makes sense, both are volcanic arcs. The Pacific coast is populated up until the Darien Gap. The Atlantic coast is probably all jungle and swamp.
As for trade routes, I think that ships might travel from harbor to harbor from Los Angeles to Panama carrying Cocaine and whatnot. However, the Pacific Coast of Colombia is all jungle and swamp. So the primary trade route from North America and the Carribean to Peru and the Southern Cone should probably have to loop from Cuba to the Lesser Antilles to the Venezuelan Coast. From there it either passes through Caracas or Maracaibo up onto the Andes. Then to Bogota and onto Peru.
But Central America should generally be pretty isolated, it's a bit of a dead end. Mexico would be this regions primary outlet to the world.
Heres a quick mockup