Under the earlier National Highway numbering system in India, which one of the following National Highways was the longest?

Introduction / Context:
Before the renumbering of National Highways in India, certain highways were well known for their length and the important cities they connected. National Highway 7, commonly written as NH 7, was traditionally described in school textbooks and reference books as the longest National Highway in the country. It ran from Varanasi in Uttar Pradesh to Kanyakumari in Tamil Nadu, covering a large north south distance. Many examination questions still refer to this earlier numbering system, so candidates must remember which highway held this record in the older scheme.

Given Data / Assumptions:

• The question explicitly refers to the National Highway system as it was traditionally known.
• NH 7 connected Varanasi to Kanyakumari under the old numbering.
• NH 2 and NH 8 were also important but shorter compared to NH 7.
• NH 15 was not as long as NH 7 in the old system.

Concept / Approach:
The conceptual approach is to treat this as a static general knowledge fact rather than a problem requiring calculation. Under the older classification, NH 7 was repeatedly mentioned in geography and GK books as the longest National Highway. It traversed multiple states from north to south. Although highway numbers and alignments have been revised, exam questions that use this traditional fact expect NH 7 as the answer unless they explicitly reference the new numbering. Therefore, you should map the question to this static fact and select NH 7.

Step-by-Step Solution:
Step 1: Identify that the question refers to the earlier highway numbering and asks about the longest highway.Step 2: Recall that NH 7 was traditionally considered the longest highway, running from Varanasi to Kanyakumari.Step 3: Recognise that NH 2 and NH 8, although important, were shorter routes in comparison.Step 4: Choose National Highway 7 (NH 7) as the correct answer.

Verification / Alternative check:
You can verify this by remembering clusters of related facts. For example, NH 2 connected Delhi and Kolkata, NH 8 connected Delhi and Mumbai, and NH 7 ran from Varanasi to Kanyakumari, clearly covering a longer north south span than the other two. This mental comparison of approximate distances confirms that NH 7 is associated with the maximum length under the old system. Most exam guides and government pamphlets from that period also reiterate this fact.

Why Other Options Are Wrong:
Option A, NH 2, is wrong because while it is an important east west corridor, it is shorter than NH 7. Option C, NH 8, is wrong because it mainly connected Delhi to Mumbai and is again shorter. Option D, NH 15, is not listed in standard sources as the longest National Highway. Only option B, NH 7, matches the established static GK fact of being the longest National Highway in India under the earlier numbering scheme.

Common Pitfalls:
One common pitfall is confusion created by the renumbering of highways, which may lead candidates to doubt older facts they learnt in school. Another mistake is mixing up highways by looking only at the numbers and not recalling their routes. To avoid such errors, make a note in your preparation that unless specified otherwise, exam questions on highway length are usually framed with the older NH numbers in mind, with NH 7 being the longest.

Final Answer:
Under the earlier National Highway numbering system, National Highway 7 (NH 7) was the longest National Highway in India.