One of the main historical problems in the construction of modern States in Latin America was the creation of a form of coactive power under the strict and exlusive control o constitutional authorities. This paper analyzes how this process  began in Mexico and Argentina with the actions  undertaken during the  preliminary agreements of Ayutla (1854) and  San Nicolas (1852)  and the debate of constituent assemblies. These two case studies were chosen because, according to recent studies on the  nineteenth- century political transition process, the same process of territorial fragmentation of control over coactive means had a very different evolution in the  two countries, regarding the ability to consolidate the State's coactive power and to use it as an instrument to strengthen a new constitutional order. This work tries to understand the historical  and cultural causes of the differences.