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  • Writer's picturehelenmakesmaps5

A guide to free GIS data sources

Updated: Jul 3, 2023

I've been working with GIS data since *gulp* about 2009. Along this journey, I've used a lot of different open data sources to gather data to help with my work - so I thought I'd put them together in a guide!


💡 The data listed here is free - but that doesn't mean it doesn't have a license! Always check the terms of use of data - as a minimum, most open data providers require you to cite them as the source of the data. This is really good practice too - if you can show that your data came from an authoritative source, that gives your analysis that bit more clout!




 

Global open GIS data sources

Topographic

Natural Earth

Really easy to use and useful, but quite limited application.


Natural Earth are a provider of free global topographic data. The data is particularly appropriate for small-scale data visualization and reference mapping, but it isn’t typically detailed or accurate enough for a lot of spatial analysis.


One thing to be mindful of with Natural Earth data is that their national boundaries are “de facto” (in fact) rather than “by law” - i.e. they show the situation as it is on the ground. This can result in your visualizations becoming very “political,” (I've had big problems with this!) and it may be worth utilizing their “disputed boundaries” layer to help navigate this.


You can download both vector and raster versions of this data.


A map showing ocean depth viewed from the North & South poles
Natural Earth also has ocean bathymetry data - mapped here!



OpenStreetMap

The OG open GIS data. Couldn't be without it.


You may have heard OpenStreetMap referred to as the Wikipedia of maps. It’s an incredibly detailed, global, crowd-sourced topographic dataset that can be used as basemap tiles or vector data.


As a crowd-sourced dataset, the most important thing to consider here is data quality. In some areas - particularly urban centres - it’s incredibly detailed and accurate, whilst in others it’s sparser. The content of the data can also vary. However, it remains one of the richest free datasets available and - in some parts of the world - is the only way spatial data analysis is possible. I find it absolutely indispensable.


I've written a full guide to this data - including when to use it and when not to - here.


You can access OpenStreetMap in a variety of ways. My preferred methods are:

  • For smaller areas (city-scale and below), I like to use the QuickOSM QGIS plugin

  • For large areas and bespoke downloads, Google BigQuery's Public Data MarketPlace is a great resource. I've written a full guide to accessing the data from this location here.

  • For bulk-downloads, it's got to be GeoFabrik.

A map showing every toilet listed on OpenStreetMap. Lighter areas signify more toilets; these are typically around Europe, Japan, and coastal areas of America & Australia.
A map showing every toilet listed on OpenStreetMap, with light blue dots signifying more toilets. Top data journalism here.
 

Social, demographic and economic data

WorldPop

So useful!


WorldPop develops peer-reviewed research and methods which allows them to create high-resolution spatial data on population distributions, demographic and dynamics. Data includes gridded population, dependency ratios, flight and migration data.


The detail here is incredible, and it's super useful to have demographic data all in one place - rather than having to refer to individual country censuses.


World Bank

Great range and quality of data. I find searchability a little tough.

An excellent source for global development and economic data. Most of the datasets available are tables, and to use for spatial analysis they must be joined to a geometry table such as the World Bank boundary layers (found here).



UN Data Portal: Population Division

Feels more focused on data visualization and stats than being a data resource. Searchability is also a bit tricky - it feels like you really need to know what you're looking for.

This catalogue mostly contains population change and demographic data. Like the World Bank data, needs to be joined to a geometry dataset to be used in spatial analytics.


NASA’s Socioeconomic and Demographic Center

Great resource but the UI feels a little old school. Like a lot of scientific/academic focused data hubs, it feels like there's a lot of method and citation pre-amble before getting to the data.

The flagship dataset from this platform is a gridded population of the world which includes variables such as age, education, and density. Many more demographic datasets are available here, such as night time lights, crop statistics, disaster locations and climate change risk.

 

Environmental & physical

USGS Earth Explorer

Love this - have used a million times! Only knocking a star off because the password requirements mean I can NEVER remember my password and have to reset it Every. Single. Time.

The USGS Earth Explorer is one of the biggest sources of global remotely sensed data.

Data includes Digital Terrain Models (DTMs), aerial imagery, radar, data from drones and more! While not all layers can be found for all parts of the world, this is a truly excellent source for remotely sensed data.


Open Topography

A useful resource but I haven't used it too much as it's focus is so US-centric, but @725Hemeed on Twitter said they use it every day and it's great, so 4 stars it is!

Another excellent source of remotely sensed data, OpenTopography specializes in elevation data and - in particularly - detailed localized surveys. Whilst most of the data here is for the the United States, it has some coverage internationally tool.


NASA Earth Observations

Fantastically clear and easy UI compared to a lot of similar platforms, and really interesting data! I only wish I had more reasons to use it.

Seriously, where would we be without NASA? Not making this list, that's for sure!

A huge catalogue of environmental change data, from sea surface temperatures to rainfall to temperature anomalies. All covering the whole world.



European Space Agency Climate Change Initiative

A quirky UI (see below) that I quite like, but is confusing when you initially land on the site.

Similar to the NASA platform, the CCI leverages 40 years of satellite imaging data to provide global environmental change data.


A screenshot of the ESA Climate Office dashboard.


NOAA Data Discovery Portal

Feels like a lot of work to get to the data from the home page.

An excellent resource for accessing global oceanic and atmospheric data across multiple time periods.

 

Traffic and transport

General Traffic Feed Specification (GTFS)

Indispensable if you work at all with transit, and such a great effort to standardize a really disparate data topic.

GTFS isn't a data source as such, but rather a format for government and transport companies to publish their scheduled and real-time transit data such as buses, trains and ferries. This data is typically published as a series of tables such as stops, routes and shapes. I've written a full guide to GTFS data here.


While there is no definitive location where GTFS data is published, individuals and communities have made great efforts to collate these. Some good sources for accessing this data is below.


 

Miscellaneous

CARTO Spatial Data Catalog

Super biased because I work at CARTO, but genuinely if you're a cloud data warehouse user you can find SO much here!

CARTO estimates that Spatial Data Scientists spend 70% of their time sourcing and formatting data, and so have created a data catalog for their users to easily access commonly-required datasets. These include topographic, environmental and demographic datasets. Additionally, they can purchase premium datasets from this catalog, including data on human mobility and consumer spend.


Note: you will need a CARTO account to access this data.


Google BigQuery Public Data Marketplace

Being cloud-native makes working with the big datasets here so easy.

Whilst the majority of the data here is not spatial in nature, you can find many datasets here for your analysis. Examples include NOAA climate data, NYC private vehicle trip data and the full historical OpenStreetMap catalogue.


A map showing hurricane tracks as glowing green lines.
A map of historic global hurricanes. Data from Google BigQuery Public Marketplace. Map created in CARTO.
 

UK open GIS data sources

General data catalogues and signposting tools

Such a useful resource. Knocking off a star because there is SO much data here, that it can actually be hard to find specific sources.

In the UK, it can be quite difficult to pinpoint the data you need. This may be because many different government agencies will have their own data portals, and it can be difficult to know where to look. On the other hand, some local agencies - such as transport bodies or local councils - may also have their own data portals, or may produce their own local datasets.

Data.gov.uk is a really excellent data resource for helping with this.. Whilst not exhaustive, it acts as a centralised data signposting tool for the UK and includes both national and local datasets.


Local and regional data catalogues

Many useful datasets are not collated or managed at a national level, such as future housing developments or road traffic schemes.

Often these can be found at Data.gov.uk, but if not it is worth searching for whether the relevant local or subregional council has a data portal, as many will.

A non-exhaustive list of some of the major local data catalogues is below:


 

Topographic

Ordnance Survey

Can't imagine doing GIS in a country WITHOUT the OS! Particularly love the ease of working with WFS layers.

There’s really only one topographic data source you need to know about in GB, and that’s the Ordnance Survey. Their data includes boundary lines, elevation, postcode centroids and more general topographic data such as roads and buildings. All of this can be downloaded or accessed via API.

The majority of Ordnance Survey data is free, with some exceptions like their most detailed layer; OS Mastermap. If you need your analysis to be so precise that you need to know the width of a road rather than just it’s centerline, then you may need this dataset. These can be purchased from OS Partners.


Ordnance Survey Northern Ireland

It’s worth noting that the Ordnance Survey’s remit doesn’t extend to Northern Ireland - for this area you’ll need to use data from OSNI, which can be found at the link.

 

Boundaries

Office for National Statistics Open Geography Portal

This data is essential, and I love the range of formats available - I just find the search function on here pretty poor and it makes for a pretty bad experience.

The ONS Open Geography Portal contains a wide range of spatial datasets which can be connected to a wide range of social, demographic and economic data. These boundaries include:

  • Administrative

  • Census

  • Healthcare

  • Electoral

In addition to this, this portal includes a range of guides and lookups between the various zone hierarchies. Most of of the data here relates to England & Wales, although some GB & UK-wide geographies are available.



National Records of Scotland

Takes a lot of clicks to drill down to the information you need - hence why I've included the below link rather than the homepage.

A range of datasets and documentation for Scotland. Please note that Scotland has held its most recent census in 2022 (unlike England, Wales & Northern Ireland) and so its most recent geography layers are for 2021.


Northern Ireland Statistics and Research Agency

Simple and easy. Like it.

As with topographic data, boundary data for Northern Ireland is maintained by a different organization.

The NISRA data portal includes administrative and census zones, as well as gridded data and postcode centroids.

 

Social, demographic and economic data

NOMIS

The UI could probably be improved, but I have used NOMIS so much in my life that I feel I could navigate it with my eyes closed - the sign of a truly valuable resource!

NOMIS is the UK’s largest producer of statistical data. Here, you can find data from:

  • The census (dating back to 1921) for wide-ranging social and demographic statistics

  • Population estimates (for between-census years) and projections up to 2118

  • Various employment surveys for understanding the distribution of jobs

  • UK business counts

  • Pension and benefits provision

And more! You can download entire tables, or query tables to extract just the information you need. I normally use the query function for everything because I find it easiest.


Please note that - due to the way data is collected - Scotland may not always be present.


Scotland Census

Simple and easy for bulk downloads.

As the Scottish Census is collected separately to England & Wales’, you can find tables from this source here.

It’s important to note that while England, Wales & Northern Ireland performed their most recent census in 2021, Scotland performed their census a year later in 2022. This was to avoid an outlier year caused by the impacts of the Covid-19 pandemic and subsequent lockdowns.


Northern Ireland Statistics and Research Agency

Feels like a lot of work to get to the data.

Data from Northern Ireland’s Census - as well as other statistics such as on the themes of trade and economy - can be found here.

 

Environmental and physical data

Natural England

Natural England are pretty top tier for sharing & producing data.

Natural England is a government advisor for protecting England’s Natural Landscape for environmental and recreational value. As such, their data covers environmental constraints (such as SSSIs), habitat inventories and landscape access data.


Defra Survey Data

The LiDAR data is just *chefs kiss.* We have no choice but to stan.

Another great source for environmental data is the government department DEFRA all of their data can be sourced via data.gov.uk.

One element of this worth highlighting is Defra’s survey data, which can be accessed at the link. Some of the fantastic data you can access from here includes:

  • LiDAR data covering around 70% of England. LiDAR data is essentially elevation data collected with a laser; it’s really accurate and super detailed. In parts of the country, the data has a resolution as low as 50cm (which means one pixel in the data covers a 50x50cm square on the ground).

  • Vertical and oblique (i.e. angled, like a bird’s eye view) aerial photography.

  • Bathymetry and surf-zone elevation data.


A map showing a 3D model of Central London
DEFRA LiDAR data
 

USA... coming soon!



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