The event was styled as a peace ride to promote the national sovereignty, but it also was a slap at Daniel Ortega, the Nicaraguan president, who has been trying to dredge a new mouth for the river.
Luis Liberman Ginsburg, one of the nation’s vice presidents, was there to welcome the crowd.
The central government put the highway in to provide an alternate route to traveling on the river that Nicaragua frequently restricts. Nicaragua has complained to the World Court about alleged environmental damage.
Costa Rica has filed its own case against Nicaragua in the World Court in which it says the neighboring county has invaded Costa Rican territory. This was possible, in part, because the northern area along the border had been neglected for years by the central government.
The Nicaraguan situation has generated substantial development of infrastructure along the river. That includes extending power lines and providing piped water.