Trailing-end guardrail anchorage systems are widely used by most state departments of transportation (DOTs) and generally consist of simple adaptations of crashworthy end terminals. The safety performance and structural capacity of these trailing-end anchorage systems, when reverse-direction impacts occur near the end, is imperative in crashworthiness of guardrail systems. In 2013, a non-proprietary trailing-end anchorage system with a modified breakaway cable terminal (BCT) was developed by the Midwest Roadside Safety Facility (MwRSF) for the Midwest Guardrail System (MGS). Although this trailing-end guardrail anchorage system adequately met the Manual for Assessing Safety Hardware (MASH) TL-3 safety requirements, the use of two breakaway wood posts was deemed by some users to have several drawbacks. Thus, there was a critical need to develop a non-wood option to anchor the downstream end of the W-beam guardrail system, which led to the need to develop a steel-post trailing-end guardrail anchorage system for use with the MGS. Following the design and component testing of such a system, two full-scale crash tests were performed according to the MASH 2016 test designation nos. 3-37a and 3-37b. In the first test, a 2270P pickup truck struck the guardrail system and was adequately contained and redirected. In the second test, an 1100C small car struck the barrier and safely gated through the barrier. Both tests were deemed acceptable according to TL-3 safety criteria in MASH 2016. Recommendations are provided for the installation of a steel-post trailing-end guardrail anchorage system when used in combination with MGS.