# Santiago–Tuguegarao Road

Santiago–Tuguegarao Road is a major national primary road in the provinces of Cagayan, Kalinga, and Isabela in the Philippines. It is a bypass road of the Pan-Philippine Highway, also known as Cagayan Valley Road, connecting to the cities of Tuguegarao and Santiago.
The road is designated as National Route 51 (N51) of the Philippine highway network.

## Route description
### Santiago to Cabatuan

Santiago–Tuguegarao Road starts at Mabini Junction, a roundabout intersection with Maharlika Highway and R.C. Miranda Road in Barangay Mabini, Santiago City. Heading north, it then runs straight to the north where it traverses the municipalities of Ramon, San Mateo, and Cabatuan in Isabela.

### Cabatuan to Santa Maria

At the poblacion of Cabatuan, the road turns north at its intersection with Santiago–Tuguegarao Bypass Road, where the Triangle Park is situated. It then crosses the Magat River vis Magat Bridge and traverses the municipalities of Aurora, San Manuel, Roxas, Mallig, and Quezon in Isabela before entering the province of Kalinga. In Kalinga, it traverses the lowland municipalities of Tabuk, the province's capital, and Rizal, away from their poblacions. It then re-enters Isabela and traverses the municipalities of Santo Tomas and Santa Maria.

### Santa Maria to Tuguegarao

In Santa Maria, Isabela, the road makes a sharp left turn at its intersection with Cabagan–Santa Maria Road. It then enters the province of Cagayan and traverses the municipalities of Enrile and Solana, where it turns east at its intersection with Cagayan–Apayao Road. It crosses the Cagayan River through the Buntun Bridge and enters the city of Tuguegarao. Approaching the poblacion, it assumes local street names such as Luna Extension and Luna Street, respectively. At its intersection with Rizal Street, west of the Tuguegarao Cathedral, it turns north and assumes such local street name. It then turns northeast towards the Balzain Bridge II and becomes Balzain Highway. The road ends at the Tuguegarao Junction, a roundabout intersection with Maharlika Highway (Cagayan Valley Road) and Tuguegarao Diversion Road II.

## Intersections

Intersections are numbered by kilometer post, with Rizal Park in Manila designated as kilometer zero.
| Region | Province | City/Municipality | km | mi | Destinations | Notes |
| Cagayan Valley | Isabela | Santiago | 327 | 203 | AH 26 (N1) (Maharlika Highway) / R.C. Miranda Road | Southern terminus. Roundabout intersection. |
| Cagayan Valley | Isabela | Ramon | 340.5 | 211.6 | Burgos–Aguinaldo Road | |
| Cagayan Valley | Isabela | Ramon | 341.8 | 212.4 | N224 (Banaue–Mayoyao–Alfonso Lista–Isabela Road) | |
| Cagayan Valley | Isabela | San Mateo | 350.9 | 218.0 | Alicia–San Mateo Road | |
| Cagayan Valley | Isabela | Cabatuan | 361.9 | 224.9 | N53 (Santiago–Tuguegarao Bypass Road) | South end of bypass. |
| Cagayan Valley | Isabela | Cabatuan | 363.3 | 225.7 | N53 (Santiago–Tuguegarao Bypass Road) | North end of bypass. |
| Cagayan Valley | Isabela | Roxas | 382.6 | 237.7 | Gamu–Roxas Road | |
| Cagayan Valley | Isabela | Mallig | 392.7 | 244.0 | Ilagan–Delfin Albano–Mallig Road | |
| Cagayan Valley | Isabela | Santa Maria | 432 | 268 | N220 (Cabagan–Santa Maria Road) | |
| Cagayan Valley | Isabela | Quezon | 408.7 | 254.0 | Abbut–Agbannawag Road | |
| Cordillera Administrative Region | Kalinga | Rizal | 419.6 | 260.7 | Rizal National Road | |
| Cagayan Valley | Isabela | Santa Maria | | | Cabagan–Santa Maria Road | |
| Cagayan Valley | Cagayan | Enrile | 437 | 272 | N52 (Kalinga–Cagayan Road) | |
| Cagayan Valley | Cagayan | Solana | 452 | 281 | Cagayan–Apayao Road | |
| Cagayan Valley | Cagayan | Tuguegarao | | | N106 (Tuguegarao Diversion Road II) | |
| Cagayan Valley | Cagayan | Tuguegarao | | | N107 (Tuguegarao Diversion Road I) | Locally known as College Avenue; south end of bypass |
| Cagayan Valley | Cagayan | Tuguegarao | | | Rizal Street | Road assumes the name Rizal Street. |
| Cagayan Valley | Cagayan | Tuguegarao | | | N107 (Tuguegarao Diversion Road I) | Locally known as College Avenue; north end of bypass. Road assumes the name Balzain Highway. |
| Cagayan Valley | Cagayan | Tuguegarao | 456 | 283 | AH 26 (N1) (Cagayan Valley Road) / N106 (Tuguegarao Diversion Road II) | Northern terminus. Roundabout intersection. |
| 1.000 mi = 1.609 km; 1.000 km = 0.621 mi |||||||

## Santiago–Tuguegarao Bypass Road

The Santiago–Tuguegarao Bypass Road is short bypass of Santiago–Tuguegarao Road in Cabatuan, Isabela. This bypass road is designated as National Route 53 (N53) of the Philippine highway network. It connects Cabatuan, Luna and Cauayan.