The northeast became a leader in commerce because of its

The Northeast became a leader in commerce because of its location and early development of industrial industries. The Northeast became a manufacturing hub in the colonies and in the newly formed United States which created specialization and the growth of commerce in this region relative to the South which was more agriculturally based. 

Answer volcanic eruptionsseismic waves from earthquakes;

Answer after wwii, communist countries in eastern europe formed the warsaw pack, a military alliance, and comecon, an economic alliance;