It is of great significance to investigate the causes of poverty in contiguous destitute areas from the perspective of regional coordinated development. Previous research on this issue are mostly qualitative studies, while this paper applies the framework of economic geography, and uses analysis of variance, impulse response functions along with linear regression to research on the relationship between causes of contiguous destitute areas and their internal provincial boundaries, taking Luoxiao mountainous area as an exemplar. Main conclusions reveal that, counties of the same contiguous destitute area but from different provinces exhibit significant differences on economic development, and provincial boundaries exert negative influences on diffusion effects induced by nearby growth poles. This study enhances our understanding on how lack of coordination among distinctive administrative units undermines economic diffusion, and indicates in-depth causality of why contiguous destitute areas exist, which is of great significance for poverty alleviation.