How Can I Create a List of Values to Be Iterated Through via WordPress Customization API?

Assuming you have an array $locations available, you can use this code to generate a dropdown in the customizer. It’s not that different from a single value.

$section_name="wpse213980_section_name"; // adapt to your naming system
$section_title="wpse213980_section_title"; // adapt to your naming system
$setting_name="wpse213980_setting_name"; // adapt to your naming system
$setting_field_type="select";
$setting_field_options = $locations;
$sanitize_callback = 'sanitize_text_field';

$wp_customize->add_setting($setting_name, array(
  'default'                 =>  '',
  'type'                    =>  'theme_mod',
  'capability'              =>  'edit_theme_options',
  'theme_supports'          =>  '',
  'transport'               =>  'refresh',
  'sanitize_callback'       =>  $sanitize_callback
   ));

$control_args = array(
    'section'                   =>  $section_name,
    'label'                     =>  $setting_title,
    'settings'                  =>  $setting_name,
    'priority'                  =>  10,
    'type'                      =>  $setting_field_type,
    'choices'                   =>  $setting_field_options,
    );

$wp_customize->add_control( new WP_Customize_Control ($wp_customize, $setting_name, $control_args));

Props Otto.