The FBI's dossier on Chávez was obtained under the Freedom of Information Act (FOIA), which contains provisions that allowed the FBI to withhold portions of the documents from public view. Indeed, many parts—and in some cases, entire pages—have been excised from the files. Nevertheless, the collection provides a compelling window into the efforts of the farmworker movement, as well as the values and methods of the FBI itself.
In the summer of 1966, the Federal Bureau of Investigation's (FBI) field offices in San Antonio and Houston sent a series of transmission describing a march from Rio Grande City to Austin by striking farm laborers in Texas. Led by the National Farm Workers Association (NFWA) and later the United Farm Workers (UFW), workers began a strike against melon growers on June 1, 1966. Between the Fourth of July to Labor Day, NFWA leader Eugene Nelson led a march to Austin, which was modeled after the march to Sacramento launched by UFW leader, César Chávez to draw support for the Delano Grape Strike in California earlier that year.
In memos dated June 28 and, 1966, the San Antonio field office noted plans for the march as reported in local papers and by an unnamed source.
A July 4 report by the San Antonio field office stated that about 100 people participated in the first leg of the march from Rio Grande City to Sullivan City, Texas. Subsequent documents from the San Antonio and Houston field offices describe the number of participants, leaders, and gatherings related to the march at different stops, including reports on July 5 (La Joya), July 7 (San Juan), July 13 (Elso and La Villa), July 14 (Raymondville), July 19 and 20 (San Manuel), July 22 (Rachael and Falfurrias), July 23 (Falfurrias and Premont), July 26 (Kingsville), August 29 (Robstown and Corpus Christi), August 5 (Gregory), August 17 (Beeville, Normanna, Pettus, Kenedy), August 24 (Karnes City, Falls City, Poth, Floresville), and August 31 (Floresville and New Braunfels).
Sent by the Houston field office, a transmission dated August 10 noted that the director of the Dallas United Auto Workers had presented Nelson with a $1,000 check at a rally for the marchers in Mathis, Texas, which included approximately 800 people.
A document dated September 5 stated that the march ended at the Texas state capitol in Austin with speeches by union leaders, as well as U.S. senator Ralph Yarbrough and U.S. representative Henry B. Gonzalez. According to a September 7 airtel, Texas governor John Connally had met with the marchers near New Braunfels on August 31, at which time he rejected their demands for a minimum wage law and refused to receive them at the Labor Day rally in Austin.