The bus system represents the most widely used transit mode. Upgraded bus services, primarily those which have partially or fully separated rights-of-way, represent a very cost effective method to improve the balance between automobile and transit. Many measures for improving bus services were introduced since 1970. However, many of these improvements were not maintained: buses were gradually returned to operations in mixed traffic. The report examines the quality of bus services in various cities in North America and worldwide and analyzes the reasons for the phenomenon of “backsliding” or disappearance of bus transit priority measures.