Grasslands around the world have experienced dramatic decline for more than a century. The spatial extent and condition of grasslands in many regions of the world are poorly understood because they lack conservation priority relative to other ecological systems. We developed a simple, yet broadly applicable rapid assessment expert system approach that can be used to assess these aspects of grassland status for improved conservation planning and management. Here we apply our approach to the semi-arid grasslands of the Arizona, New Mexico, and Mexico borderlands. We specifically used a combination of expert input and field verification. The accuracy of the expert input was 71%–77%. Native grasses dominate nearly 50% of identified grasslands. However, over two-thirds of these grasslands have experienced a moderate level of shrub encroachment. These areas may be restorable to open grassland with use of prescribed fire. Non-native perennial grasses are common to dominant on 12% of the study area. More than 67% of native grasslands occur on private and state land where there is little legal protection. In a region experiencing substantial development pressure, grasslands are at risk of becoming increasingly fragmented and vulnerable to non-native species invasion. Now, with our approach to assessing grassland status, conservation practitioners and partners are better positioned to protect and restore the remaining grasslands in the U.S.-Mexico borderlands and elsewhere.