At Salinas, the road turns north to cut through the Cordillera Central in its approach to San Juan.

One of the major roads in Ponce that PR-1 does not intersect is PR-10, which is accessible via an alternate route (PR-5506) through Mercedita Airport.

It becomes a divided road once again from Caguas to San Juan at a sector known as "La Muda".

Prior to PR-52's inauguration, PR-1 was the route of choice from traveling between Ponce and San Juan.

Construction of what became PR-1 began with the building of the Carretera Central, started during the governorship of Miguel de la Torre (1822–1837).