diff --git a/core/modules/datetime_range/config/schema/datetime_range.schema.yml b/core/modules/datetime_range/config/schema/datetime_range.schema.yml
index f0f93259d3..f4765d37d5 100644
--- a/core/modules/datetime_range/config/schema/datetime_range.schema.yml
+++ b/core/modules/datetime_range/config/schema/datetime_range.schema.yml
@@ -5,6 +5,10 @@
 field.storage_settings.daterange:
   type: field.storage_settings.datetime
   label: 'Date range settings'
+  mapping:
+    optional_end_date:
+      type: boolean
+      label: 'Optional end date'
 
 field.field_settings.daterange:
   type: field.field_settings.datetime
diff --git a/core/modules/datetime_range/src/DateTimeRangeTrait.php b/core/modules/datetime_range/src/DateTimeRangeTrait.php
index 3f05b82189..806e93ff98 100644
--- a/core/modules/datetime_range/src/DateTimeRangeTrait.php
+++ b/core/modules/datetime_range/src/DateTimeRangeTrait.php
@@ -17,13 +17,13 @@ public function viewElements(FieldItemListInterface $items, $langcode) {
     $separator = $this->getSetting('separator');
 
     foreach ($items as $delta => $item) {
-      if (!empty($item->start_date) && !empty($item->end_date)) {
+      if (!empty($item->start_date)) {
         /** @var \Drupal\Core\Datetime\DrupalDateTime $start_date */
         $start_date = $item->start_date;
         /** @var \Drupal\Core\Datetime\DrupalDateTime $end_date */
         $end_date = $item->end_date;
 
-        if ($start_date->getTimestamp() !== $end_date->getTimestamp()) {
+        if ($end_date !== NULL && $start_date->getTimestamp() !== $end_date->getTimestamp()) {
           $elements[$delta] = [
             'start_date' => $this->buildDateWithIsoAttribute($start_date),
             'separator' => ['#plain_text' => ' ' . $separator . ' '],
diff --git a/core/modules/datetime_range/src/Plugin/Field/FieldType/DateRangeItem.php b/core/modules/datetime_range/src/Plugin/Field/FieldType/DateRangeItem.php
index 7c34ed127c..a6755abf2b 100644
--- a/core/modules/datetime_range/src/Plugin/Field/FieldType/DateRangeItem.php
+++ b/core/modules/datetime_range/src/Plugin/Field/FieldType/DateRangeItem.php
@@ -24,6 +24,15 @@
  */
 class DateRangeItem extends DateTimeItem {
 
+  /**
+   * {@inheritdoc}
+   */
+  public static function defaultStorageSettings() {
+    return [
+      'optional_end_date' => FALSE,
+    ] + parent::defaultStorageSettings();
+  }
+
   /**
    * Value for the 'datetime_type' setting: store a date and time.
    */
@@ -44,9 +53,10 @@ public static function propertyDefinitions(FieldStorageDefinitionInterface $fiel
       ->setClass(DateTimeComputed::class)
       ->setSetting('date source', 'value');
 
+    // @todo Write a comment on why we can't use the $field_definition here.
     $properties['end_value'] = DataDefinition::create('datetime_iso8601')
       ->setLabel(t('End date value'))
-      ->setRequired(TRUE);
+      ->setRequired(FALSE);
 
     $properties['end_date'] = DataDefinition::create('any')
       ->setLabel(t('Computed end date'))
@@ -83,6 +93,12 @@ public function storageSettingsForm(array &$form, FormStateInterface $form_state
 
     $element['datetime_type']['#options'][static::DATETIME_TYPE_ALLDAY] = $this->t('All Day');
 
+    $element['optional_end_date'] = [
+      '#type' => 'checkbox',
+      '#title' => t('Optional end date'),
+      '#default_value' => $this->getSetting('optional_end_date'),
+    ];
+
     return $element;
   }
 
@@ -94,6 +110,7 @@ public static function generateSampleValue(FieldDefinitionInterface $field_defin
 
     // Just pick a date in the past year. No guidance is provided by this Field
     // type.
+    // @todo Do we need to update this?
     $start = REQUEST_TIME - mt_rand(0, 86400 * 365) - 86400;
     $end = $start + 86400;
     if ($type == static::DATETIME_TYPE_DATETIME) {
@@ -112,6 +129,10 @@ public static function generateSampleValue(FieldDefinitionInterface $field_defin
    */
   public function isEmpty() {
     $start_value = $this->get('value')->getValue();
+    if ($this->getFieldDefinition()->getFieldStorageDefinition()->getSetting('optional_end_date')) {
+      return $start_value === NULL || $start_value === '';
+    }
+
     $end_value = $this->get('end_value')->getValue();
     return ($start_value === NULL || $start_value === '') && ($end_value === NULL || $end_value === '');
   }
diff --git a/core/modules/datetime_range/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php b/core/modules/datetime_range/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php
index 85fda9ba53..996b71c456 100644
--- a/core/modules/datetime_range/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php
+++ b/core/modules/datetime_range/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php
@@ -19,6 +19,7 @@ class DateRangeWidgetBase extends DateTimeWidgetBase {
    */
   public function formElement(FieldItemListInterface $items, $delta, array $element, array &$form, FormStateInterface $form_state) {
     $element = parent::formElement($items, $delta, $element, $form, $form_state);
+    $optional_end_date = $this->getFieldSetting('optional_end_date');
 
     // Wrap all of the select elements with a fieldset.
     $element['#theme_wrappers'][] = 'fieldset';
@@ -27,9 +28,13 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
     $element['value']['#title'] = $this->t('Start date');
 
     $element['end_value'] = [
-      '#title' => $this->t('End date'),
+      '#title' => $optional_end_date ? $this->t('End date (optional)'): $this->t('End date'),
     ] + $element['value'];
 
+    if ($element['#required'] && $optional_end_date) {
+      $element['end_value']['#required'] = FALSE;
+    }
+
     if ($items[$delta]->start_date) {
       /** @var \Drupal\Core\Datetime\DrupalDateTime $start_date */
       $start_date = $items[$delta]->start_date;