Shortly after the proclamation of the Kingdom of Italy in Turin, on 22 March 1862, the Italian-San Marino Treaty was signed between the President of the Italian council Urbano Rattazzi and the Sammarinese Captains Regent Melchiorre Filippi and Domenico Fattori.

In 1951, the Italian interior minister Mario Scelba had imposed a police blockade in San Marino to force it to close the newly opened casino.

The tension ended with the stipulation of the agreements of 1953, with which San Marino renounced both the gambling house and the system of a radio or television broadcaster.

Furthermore, the same day the Voluntary Militia Corps was dissolved, fearing the armed intervention of the Provisional Government supported by Italian soldiers towards the Public Palace.

Since then, San Marino was led until the end of the Cold War by anti-communist forces with a foreign policy close to Italy and the United States which led to the construction of the Rimini-San Marino highway; the works began on 10 August 1959, and it was inaugurated in the presence of the President of the Italian Republic Giuseppe Saragat on 25 November 1965, who met the Captains Regent Alvaro Casali and Pietro Reffi at the Palazzo Pubblico.

On 20 October 1984, the President of the Republic Sandro Pertini met the newly elected Captains Regent Marino Bollini and Giuseppe Amici.

The unresolved problems between Italy and San Marino concern the status of the 6,000 Italian migrant workers in relation to the lack of an agreement between the two states and the introduction of a San Marino tax levy on frontier workers of 200 euro on 12 January 2011, the question had reached the Foreign Affairs Committee of the Chamber of Deputies on 23 February and on 16 February it provoked a parliamentary question by the Minister of Finances Giulio Tremonti.