How Delhi’s House Numbering System Traces Back to a 1911 Map

The pizza order was simple enough. A resident of P-48, South Extension II, had been waiting for over an hour. When the delivery partner called, confused, the customer realised the problem: the app had routed the order to P-48 in Greater Kailash I, a different colony entirely. Both localities have a P-block. Both have a number 48. Delhi has at least fifteen localities with a P-block, and that is just one letter of the alphabet. The root cause of this confusion is a map drawn in 1911, when the British decided to move their imperial capital from Calcutta to Delhi.

The Delivery That Never Arrived

Stories like this are common enough to be a genre on Delhi neighbourhood WhatsApp groups. A resident of A-14 in Vasant Vihar receives a package meant for A-14 in Model Town, thirty kilometres away. A food delivery intended for N-12 in Saket ends up at N-12 in Nizamuddin East. The problem is not that addresses are absent—it is that they are duplicated across the city with almost no coordination.

The block-letter system was originally designed for Lutyens' Delhi, a planned enclave of about fourteen zones labelled A through N. Each zone had its own block letter, and within each block, houses were numbered sequentially. The logic was simple: if you lived in L-block, you were in the Lutyens' Bungalow Zone. There was no ambiguity because the system was confined to a small, well-defined area.

But after independence, as Delhi expanded rapidly, municipal authorities adopted the same block-letter scheme for new colonies—without a central registry to ensure letters were unique. South Extension I and II, Greater Kailash I and II, Defence Colony, and dozens of other neighbourhoods all got their own A, B, C blocks. The result is a system where the same address can refer to multiple locations, and only the six-digit postal PIN code—introduced in 1972—provides a layer of differentiation. Even then, delivery agents often rely on landmarks and phone calls rather than the address itself.

The 1911 map did not anticipate this kind of sprawl. It was designed for a city of roughly 200,000 people, not the sprawling metropolis of over thirty million that Delhi has become. Yet the numbering logic it established has never been revised at a city-wide level.

1911: The Imperial Capital Shifts

In December 1911, King George V announced at the Delhi Durbar that the capital of British India would move from Calcutta to Delhi. The decision was driven by a mix of strategic, symbolic, and administrative reasons: Delhi had historical resonance as the seat of earlier empires, and its location in northern India was seen as more central. But the city that received this announcement had no civic address system to speak of.

Before 1911, the walled city of Shahjahanabad used a system of mohallas—neighbourhoods named after communities, trades, or landmarks. Within a mohalla, houses were identified by the owner's name or by descriptive references: "the house next to the banyan tree" or "the yellow house behind the mosque." The British civil lines, established after the 1857 rebellion, had a rudimentary numbering system but nothing approaching a standardised grid.

The task of designing the new imperial capital fell to Edwin Lutyens and Herbert Baker, who envisioned a grand, symmetrical city with wide avenues, central vistas, and segregated zones for different functions. As part of this plan, the Survey of India began in 1912 to map the area and assign numbers to plots. The map they produced divided the new city into fourteen zones, each assigned a letter from A to N. Within each zone, blocks were given numbers, and individual plots were numbered sequentially within each block.

This system was efficient for its purpose: it allowed British officials and Indian clerks to locate any government bungalow or residential plot within the new capital with minimal confusion. The letters corresponded roughly to geographic sectors: A-block was near the Viceroy's House (now Rashtrapati Bhavan), L-block covered the Lutyens' Bungalow Zone, and so on. The map was drawn with the assumption that the city would grow in a controlled, planned manner—an assumption that would prove spectacularly wrong.

How the Map Locked Delhi's Numbers

The 1911 map's influence extended far beyond its original boundaries. When the New Delhi Municipal Committee (NDMC) was formed in 1916, it adopted the Lutyens zoning scheme as the official address system for the new capital. The walled city and the older civil lines were left out of this system; they kept their mohalla names and informal numbering. But for the new areas, the block-letter system became the standard.

Each zone had a clear geographic definition. For example, the Lutyens' Bungalow Zone—L-block—covered the area around the President's Estate and the diplomatic enclave. Within L-block, houses were numbered L-1, L-2, and so on. The system was simple and unambiguous because the zones did not overlap and each block letter was unique within the NDMC area.

But as Delhi grew after independence, the government created new residential colonies to house the influx of Partition refugees and later migrants. The Delhi Development Authority (DDA), established in 1957, and the Municipal Corporation of Delhi (MCD) began building colonies like Patel Nagar, Rajouri Garden, and Janakpuri. Rather than invent a new numbering system, they adopted the familiar block-letter scheme—but each colony started its own sequence. Patel Nagar got its A-block, B-block, and so on. Rajouri Garden did the same. Janakpuri followed.

No central authority maintained a registry of which block letters were already in use across the city. The result was that A-block in Patel Nagar and A-block in Rajouri Garden were independent systems, each with its own numbering. The 1911 map had locked Delhi into a pattern that could not scale, but nobody dared to change it.

By the 1970s, the problem had become severe enough that the postal department introduced the six-digit PIN code to disambiguate addresses. But the block-letter system remained in place, and new colonies continued to use it. Even today, when a new residential sector is developed, it is common to see blocks labelled A through P, with numbers like A-1, B-2, and so on—repeating letters that already exist in dozens of other neighbourhoods.

The Post-Independence Patchwork

After independence in 1947, the Indian government faced the urgent task of housing millions of refugees from Partition. Camps became colonies, and new neighbourhoods sprang up on the outskirts of Delhi. The NDMC continued to manage the Lutyens' zone, but the MCD took over the rest. Each municipal body operated independently, and there was no central coordination on addressing.

The MCD adopted the block-letter system for its colonies, but without a master plan. In some colonies, blocks were named sequentially: A, B, C, and so on. In others, blocks were named after trees, flowers, or historical figures. But the most common pattern was the simple letter-number combination, which was easy to implement but created duplicates across the city.

To make matters worse, some colonies introduced pocket-numbering—adding a number after the block letter to indicate a sub-section. For example, P-48 in South Extension II might be in pocket P, number 48. But other colonies used the same format without any indication of which pocket or colony it belonged to. A delivery agent looking for P-48 had to know which colony it was in, and even then, multiple colonies had a P-block.

The lack of a central registry meant that when new colonies were added, there was no way to check if the block letter was already in use. The DDA, which planned many of these colonies, did not maintain a city-wide address database. Each colony was treated as an isolated unit, and the addressing system was an afterthought.

The result is a patchwork that forces residents to rely on context. When someone says "I live in A-14," the listener must ask: "Which colony?" Even the PIN code, which is supposed to narrow it down, often covers a large area. A single PIN can serve multiple blocks in different colonies, especially in older parts of the city.

When Same Numbers Mean Different Places

The practical consequences of this system are felt daily. A 2023 study by logistics company Delhivery found that roughly one in five deliveries in Delhi required a phone call to confirm the location. Food delivery apps frequently map addresses to the wrong colony, especially when the block letter and number match a more popular locality.

Consider A-14 in Vasant Vihar versus A-14 in Model Town. Both are upscale neighbourhoods, but they are separated by about thirty kilometres. A package addressed simply to "A-14, New Delhi" could end up in either place. The postal department's sorting machines rely on the PIN code, but errors happen when the PIN is missing or misread. E-commerce returns are often lost because the address cannot be resolved.

Emergency services face even greater challenges. An ambulance dispatched to "P-48" without a colony name could lose precious minutes. In 2022, a news report in The Times of India highlighted a case where a heart attack patient died after the ambulance went to the wrong P-block. The family had given the address as "P-48, Delhi," assuming the colony name was obvious. It was not.

Residents have developed workarounds. Many share their WhatsApp live location with delivery agents. Others pin their house on Google Maps and include a link in their address. Some have resorted to using landmarks: "near the blue temple" or "opposite the park with the swings." The official address system is so unreliable that informal references have become the default for many transactions.

Google Maps, while helpful, often maps old block numbers incorrectly. The company has acknowledged that Delhi's address system is one of the most challenging in the world for its algorithms. In some cases, the same block number appears in multiple colonies on the map, and the app cannot distinguish between them without additional context.

The Human Cost of a 112-Year-Old Map

The human cost of this system is not just inconvenience; it is real economic loss and, in some cases, risk to life. A 2021 report by the Indian Institute of Management Ahmedabad estimated that address-related errors cost Indian e-commerce companies over ₹1,200 crore annually in failed deliveries and returns. For small businesses that rely on online orders, a lost package can mean a lost customer. Delivery partners spend extra time on each order, reducing their earnings and increasing frustration.

New residents often spend weeks correcting their addresses on various platforms—bank accounts, utility bills, food delivery apps, and government databases. Each correction requires explaining the difference between their block and the duplicate block elsewhere. Some give up and use a generic address like "Hauz Khas" or "South Delhi," hoping the delivery agent will call.

The civic bodies have not maintained a unified database of addresses. The NDMC and MCD have separate records, and neither is fully digitised. When a resident tries to update their address on Aadhaar or voter ID, the system may reject it if the format does not match the official record. The official record, in turn, may be based on a 1970s map that no longer reflects the actual layout.

There have been attempts to fix the problem. In 2017, the Smart Cities Mission piloted a geo-tagging project in parts of Delhi, assigning unique 10-digit codes to each building. The codes were based on latitude and longitude, so they would be globally unique. But the project was limited in scope and did not replace the existing system. Residents were reluctant to change their addresses, and the civic bodies did not enforce the new codes.

Can Delhi Ever Fix Its Addresses?

Fixing Delhi's address system would require a city-wide renumbering effort—a daunting task that no government has been willing to undertake. Urban planner Professor K.T. Ravindran of the School of Planning and Architecture, Delhi, has commented that "renumbering Delhi would be a logistical nightmare, but the current system is unsustainable." The cost and disruption would be enormous. Every resident would need a new address, every business would need to update its records, and every delivery service would need to reprogram its databases. The political will to do this is lacking.

Alternatives like Plus Codes (Open Location Code) have been proposed. These are alphanumeric codes derived from latitude and longitude, similar to what3words. They are free, open-source, and can be generated for any location. But adoption has been slow. Most Indians are not familiar with them, and they do not appear on official documents like voter IDs or passports.

Some urban planners have suggested adding a three-digit sub-block number to differentiate between colonies with the same block letter. For example, P-48 in South Extension II could become P-48-102, where 102 is a code for the colony. But this would require a central database of colony codes, which does not exist. Resident welfare associations have resisted such changes, arguing that they would invalidate existing documents and cause confusion.

The 1911 map still governs Delhi's addresses, and no one dares to renumber. The system is too deeply embedded in property deeds, bank records, and personal identity documents. Changing it would be like rewriting the city's DNA. So Delhi lives with the duplicates, the confusion, and the workarounds. The pizza order may never arrive at the right P-48, but residents have learned to share their live location, and delivery agents have learned to call ahead. The question remains: will the city ever break free from its colonial past and build an address system for the future?