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Introduction to Geographic Information Systems (GIS)

What is GIS data?

There are two main types of GIS data: vector and raster.

Vector Data: is what people commonly work with since it is closer to the traditional method of cartographic representation and it can be summarized as spatial features combined with attributes about the feature. The spatial features are in the form of points, lines, and polygons.

Image Description: Three square images in a single row with a single word under each square. The left square has 4 differently colored dots and the word points below. The middle square has 4 blue lines connected and the word lines below. The right square has three irregular green shapes and the word polygon below.

Raster Data: is essentially stored electronic images such as aerial photographs or satellite images.

Image Description: The image is a box with gridded lines and the cells are colored to match the three vector images if they were overlaid from right to left.

Another important aspect of GIS data is the source of it. There are two types of sources: primary and secondary.

Primary Data: also known as raw data, is data collected by researchers from the main source such as interviews, surveys, experiments, etc. To learn how to gather primary data, go to our "Collect Your Own Data" section.

Secondary Data: is data gathered from studies, surveys, or experiments ran by other researchers or organizations.

Steps to Find Secondary Data

Oftentimes the secondary data you need exists online but may be difficult to find. To make your search easier, follow these steps.


First, start off by writing down what you want to display.

Example 1: I want to display all the zip codes in Las Vegas, NV.

Example 2: I want to display the sea level rising in Hawaiʻi.

Next, brainstorm possible words or phrases that are related to your research or project.

Keywords 1: zip code areas/boundaries, Las Vegas, Clark County, Nevada

Keywords 2: sea level rising, Oahu, Hawai'i, climate change, coastal flooding, etc.

These keywords will help narrow down your search.

Afterwards, list the attributes you need in your dataset. Attributes are qualities, data values, or nonspatial information connected to a geographic feature.

Attributes 1: zip code, population density, area size, median household income, etc.

Attributes 2: sea level height, perimeter, beaches, salinity, nitrate, etc.

Now you should be able to quickly decipher if a dataset is useful to you.

Finding secondary data

In this page, you will find a list of websites with data that can be used in GIS software. 

Please note that some of the data below are attribute data, meaning that it will have to be joined with geographic data (such as TIGER files) in order to be used in GIS software.

Local Data

State Data

National Data

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