2017–2022 :In its final form, the 9th district was located in the north of the state. Its head town (), where results from individual polling stations were gathered together and tallied, was the city of
Reynosa and it covered 221
electoral precincts () in the south of the
municipality of Reynosa. The remainder of the municipality was assigned to the
2nd district.
1978–1996 :Tamaulipas's seat allocation rose from six to nine under the
1977 electoral reforms, which increased the number of single-member seats in the Chamber of Deputies from 196 to 300. :*
Antiguo Morelos,
Gómez Farías,
Mante,
Nuevo Morelos,
Ocampo and
Xicoténcatl. ==Deputies returned to Congress==