Newly elected in 1880, President Julio Roca supported Rocha's candidacy as Governor of Buenos Aires Province, the nation's most important and most politically contentious at the time.

[4] Freemason architect Pedro Benoit was commissioned by Governor Rocha to plan the provincial capital city of La Plata, who created a compass pattern of diagonals and precisely-placed squares.

He was a well-known, well-connected and persuasive candidate who had secured his place among Argentina's paramount Generation of 1880; but lost the nomination to Miguel Juárez Celman, the Governor of the Province of Córdoba and President Roca's son-in-law.

He kept a low political profile following the institutional crisis of 1890 and devoted his time to the growing city he had founded, for which he established the University of La Plata in 1897 and stayed on as its president until the school's nationalization in 1905.

His additional responsibilities as Director of the Constitutional Law syllabus at the school did not precluse Rocha from accepting a commission as Argentine observer to the 1904 Bolivia-Chile Border Demarcation Treaty.