First, let's add an area map for each borough, so that we can check which regions have more collisions, as follows:

1. Drag and drop a custom object of type Area Layer, as shown in the following screenshot:

2. Configure the dimension of our layer; let's choose the borough field, as demonstrated in the following screenshot:

3. As you can see, you don't have to worry about the borough coordinates, GeoAnalytics is smart enough to understand your data and use this field as a geometry, as shown in the following screenshot:

Here, GeoAnalytics plots the base map, zooms into the corresponding area (because we have checked Zoom to Selection in the base map), plots the borough boundaries, and fills the limits with a blue color. Now, let's add more information. We will create a color gradient that is based on the collisions that occurred in the borough, as follows:

1. Select the Appearance section from the layer. Here, you're going to see a subsection called Colors, uncheck the Auto option, choose the By measure option, and select Collisions as a measure. You can set the transparency too, so that the colors are not so solid, as demonstrated in the following screenshot:

2. Your screen should look like the following:

Let's now add more information. We're going to enable our user to drill-down from the borough to the ZIP area, so that the user can conduct a deeper analysis. The easiest way to do this is by using a Qlik Sense native feature, called Drill-Down Dimension.

In order to create a dimension, perform the following steps:

1. Go to the Master items library under the Dimensions section. Here, you're going to see a Create new button, as demonstrated in the following screenshot:

2. In the Create new dimensions form, select the Drill-down option; then, select borough and zip_code as fields, and name your dimension. After this, click on Add dimension and then Done, as depicted in the following screenshot: 

3. Drag and drop this new dimension over your area layer, you will then be prompted by Qlik Sense to do what you want to do. Please choose the Replace 'borough' option, as shown in the following screenshot:

To test the map, follow these instructions:

1. Clear all selections. Your screen should then look like the following:

2. Click on Manhattan. You can see that the borough value is MANHATTAN and that all ZIP areas are shown. The map zooms in to show only the Manhattan area that has had collisions, as shown in the following screenshot:

If you clear your selections again, you're going to see that the map zooms out and only the borough borders are shown.