You can pin the map first before filtering. Otherwise you could use a Action filter to highlight the area of a map in a dashboard.
It's the pin icon under 'Rest the view' in the following online help doc Pan and Zoom
Thanks Cor. I tried to get it to work with your file as well and I could not. I ended up making a base map and layering the differing data points in Photoshop. I would think this is something that Tableau could do pretty easily but its clearly not. Thanks for your help!