The Greater Mekong Sub-region (GMS) is in Southeast Asia, including six countries: Cambodia, China, Lao PDR, Myanmar, Thailand, and Vietnam. The presence of Economic Corridors (ECs) in the GMS had brought many economic impacts potentially, in particular, in this work, three issues on international trade; FDI inflows and poverty reduction were assessed by using secondary data source and previous research work of the author at Mekong Institute. The aim of this work is to investigate the roles of transportation and its facilities to support the sub- regional economy. Logically, the book is divided into five chapters, with systematic data and comparative analysis on three mentioned issues of which ECs brought opportunities to the GMS countries; and the same comparative data and analysis for two East West Economic Corridor (EWEC) provinces - Quang Tri (Vietnam) and Savannakhet (Lao PDR). The comparisons and data analysis were approached over period before and after the presence of transportation network during 1990-2009