Quick correction, filter region stored in session was not used...

app/controllers/application_controller.rb

@@ -12,9 +12,12 @@ class ApplicationController < ActionController::Base
       http_accept_language.compatible_language_from I18n.available_locales
   end
 
+  # Mechanism to manage the region filter
   def set_filters
-    return unless params.include? :region
-    session[:region] = params[:region] == 'all' ? nil : params[:region].to_i
+    if params.include? :region
+      session[:region] = params[:region] == 'all' ? nil : params[:region].to_i
+    end
+    params[:region] ||= session[:region]
   end
 
   protected