<p>This study provides a comprehensive analysis of China’s international and inter-provincial border effects. The results confirm the significant negative impact of administrative borders on trade flows. I account for multilateral resistance terms, which previous studies using similar data frameworks omit. This omission underestimates both international and inter-provincial border effects in joint estimation. Additionally, I find a negative association between international and inter-provincial border effects. Higher international and within-provincial exports correlate with lower inter-provincial exports, though the correlation diminishes when both international and within-provincial exports expand simultaneously. This pattern may be explained by high coordination constraints associated with inter-provincial trade, reallocating shipments inward or outward rather than across provincial boundaries; however, it could also stem from alternative factors such as industrial convergence or infrastructure development. Finally, I employ the Levenshtein Distance to quantify language gaps within provinces, between provinces, and between provinces and countries. The results suggest that linguistic gap and cultural barriers potentially explain part of the observed inter-provincial border effect in China.</p>