Chronology of Catholic Dioceses:Notes on the Apostolic Vicariate of Baja California - 1874
Regarding Baja California / Lower California, according to Bravo Ugarte, p. 98: «En 1852 o 53 la Peninsula fue desmembrada de la diocesis estadounidense de Monterey y dada para su administracion al Arz. de México (Bula de ereccion de San Francisco, Calif.: Foreign Relations of the U.S., 1902, Append. II). En 1855 fue el Ob. de Anastasiopolis y su primer Vicario Apostolico el Sr. Escalante y Moreno, el cual su intitulaba "Vicario Capitular" de la Baja California (Pastoral al V. Clero y fieles de su jurisdicc. Ejemplar en la Bibl. Publ. de Guadalajara, Colecc. Impresos, XVI 853). Pero el Vicariato no se erigio hasta 1872 (Docs. Ecles. del Arz. de Guadalajara, VII 19); o hasta 1874 (Annuario Pontificio)»
An approximate translation: In 1852 or 1853 Baja California was dismembered from the Diocese of Montery and given to the Archbishop of Mexico to administer. Its first vicar apostolic was Bishop Escalante y Moreno, Titular Bishop of Anastasiopolis, who was given the title of vicar capitular. The AV was not actually erected until 1872 (according to Docs. Ecles. of the Archdiocese of Guadalajara) or 1874 (according to the Annuario Pontificio).
The above does not give Baja California any juridical status until 1874. Now we know from where Baja California was taken - but should it be considered part of the Archdiocese of Mexico from 1852/53 until 1874? I would say yes, even though it was not contiguous with the rest of the archdiocese. There are still dioceses in Italy and Germany which have parts which are not contiguous.