A Century Uncovered: Bringing the 1926 Irish Census to Life

The 1926 Irish Census is now live, opening up a remarkable view of life in Ireland a century ago. As the first census of the Irish Free State, it captures the country at a pivotal moment in its history, offering a detailed picture of how people lived, worked and formed communities in the early years of independence. Search the Census here.

This is a major national milestone, making a rich and important part of Ireland’s history more accessible, searchable and usable for everyone. With over 700,000 household returns and records relating to nearly three million people, the 1926 Census represents a significant national resource, supporting everything from academic research to personal family history.

The launch itself reflects the scale and importance of the project. The census was officially released at 00:01 on Saturday 18 April, with teams across the project online to ensure everything ran smoothly as the platform went live. Interest was immediate from the moment the platform went live. Based on performance data from the launch weekend, the scale of demand is clear:

The release was marked by a launch event in Dublin Castle, attended by the Taoiseach, Micheál Martin, and the Minister for Culture, Communications and Sport, Patrick O’Donovan, underlining the national significance of making these records publicly available.

Working with the National Archives of Ireland and their website developer Ebow over recent months, Derilinx acted as the data infrastructure partner for the project, contributing to the design and delivery of the underlying platform, powering the search, as well as developing the mapping interface to the data.

Making the Census Searchable and Usable

A key part of this release is not just making the records available, but making them usable.

The project involved taking a vast and complex dataset and structuring it in a way that allows it to be searched, filtered and accessed efficiently. Derilinx extended the process that we developed for the revamped 1901/11 census project from early 2025, building an ETL pipeline to preprocess the data and import into compressed, columnar parquet files. These files are accessed through an in-process database engine within the API to provide high speed, low latency queries. The API instances have no shared resources, so they are horizontally scalable to accommodate any load.   This enables users to move beyond static records, making it easier to explore the data in a more meaningful and practical way.

Bringing 1926 Ireland to Life Through Mapping

Alongside the search functionality, an interactive map provides a spatial way to explore the census.

The map allows users to navigate county and District Electoral Division boundaries as they existed in 1926, alongside key demographic information. As users zoom in, the map reveals the original 1926 mapping, including streets and local detail, bringing the data much closer to how people actually experienced place at the time.

This adds an important dimension to the platform, helping users understand patterns and context across different parts of the country.

Access to Original Census Returns

In addition to structured and searchable data, the platform also provides access to digitised images of the original census returns, with 3TB of image data made available.

This allows users to connect directly with the source material, moving seamlessly between structured data and the original records, and exploring the census as it was captured in 1926.

For many users, particularly those researching family history, this connection between data and original documents is a key part of the experience.

Built for Scale

Given the scale of the dataset and the level of public interest, the platform needed to perform reliably under significant demand from the moment it went live.

The solution was designed with scalability at its core, combining a robust architecture, extensive performance testing and a fully horizontally scalable deployment. The columnar database is very good at efficiently filtering and counting records, particularly important for the facet search refinement and map functionality. AWS was the technical partner, providing the infrastructure needed to handle large volumes of data and very high levels of concurrent usage, ensuring the platform remained responsive and accessible as hundreds of thousands of people explored the census at the same time.

From the moment of release, the platform handled sustained demand, reaching over 10,000 API requests per minute within minutes of launch and peaking at over 54,000 requests per minute during national media coverage on Saturday night. During the launch weekend, the system supported around 15 million user searches, while maintaining an average API latency of around 40ms, with 99^th percentile response times remaining below 700ms even at peak load.

More Than Data

The release of the 1926 Census is not just about data,  it’s about people, stories and connections across generations.

As National Archives Director Orlaith McBride said:

“The census has never been about lists and numbers; it’s the story of us. It’s about the people living in Ireland in 1926 and all of their descendants today. Whether through the centenarian ambassadors, this exhibition, the book and all the other elements of our extensive public programme, throughout this project we have aimed to ensure the stories, information and human connections revealed by the census reach as many people as possible, in Ireland and around the world.”

The National Archives is also supporting the release through the 1926 Census: The Story of Us exhibition, which explores the world reflected in the census and provides additional context around life in Ireland during this period.

Search the Census

Making a dataset of this scale accessible, searchable and explorable changes how it can be used in practice, not just for research, but for personal discovery. It allows people to move from records to stories, from data to lived experience.

For many, this will be the first time they can trace a family member, see where they lived, and understand their place in a wider community. At a national level, it provides a shared reference point, a way of looking back at who we were, and how Ireland has evolved since.

That combination of scale, accessibility and human connection is what makes this release so significant.