The breakdown of law and order on the Mexican side of the border, coupled with the lack of federal military forces, meant the Rangers were once again called upon to restore and maintain law and order, by any necessary means, which again led to excesses. However, the situation necessitated the appointment of hundreds of new special Rangers by the state, which neglected to carefully screen aspiring members. The Rangers were responsible for several incidents, ending in the January 28, 1918 massacre of the male population[23] (15 Mexican men and boys ranging in age from 16 to 72 years) of the tiny community of Porvenir, Texas, on the Mexican border in western Presidio County. Before the decade was over, thousands of lives were lost, Texans and Mexicans alike. In January 1919, an investigation launched by Texas lawmaker José Tomás Canales found that from 300 to 5,000 people, mostly of Hispanic descent, had been killed by Rangers from 1910 to 1919, and that members of the Rangers had been involved in many acts of brutality and injustice.[24] The Rangers were reformed by a resolution of the Legislature in 1919, which saw the special Ranger groups disbanded and a complaints system instituted.[25]
The Great Depression forced both the federal and state governments to cut down on personnel and funding of their organizations, and the number of commissioned officers was reduced to 45, with the only means of transportation afforded to Rangers being free railroad passes or using their personal horses. The agency was again damaged after supporting Governor Ross Sterling in his re-election campaign—after his opponent Miriam Amanda "Ma" Ferguson won, she proceeded to discharge all serving Rangers in 1933.