Which early-20th century advancement allowed trade to increase between countries on atlantic coasts and countries with pacific coasts

The correct answer is the Panama Canal. The Panama Canal is a strategic, man-made waterway that connects the Atlantic and Pacific Oceans. Its construction was finished in 1914. The canal increased trade between countries on opposing coasts, because instead of having to sail all the way around gigantic continents to reach one another, the countries could simply cut through the canal.

Who what do u think?

Dcalifornia they have the most people with 200+ people per square mile