diff --git a/assets/tailwind.config.js b/assets/tailwind.config.js
index be9b51dea7..e12c5e97f2 100644
--- a/assets/tailwind.config.js
+++ b/assets/tailwind.config.js
@@ -42,7 +42,8 @@ module.exports = {
         },
         "brand-primary": {
           DEFAULT: "#165c96",
-          darkest: "#0b2f4c"
+          darkest: "#0b2f4c",
+          lightest: "#cee0f4"
         },
         "logan-express": {
           BB: "#f16823",
diff --git a/lib/dotcom_web/components/live_components/trip_planner_results_section.ex b/lib/dotcom_web/components/live_components/trip_planner_results_section.ex
index 744336336d..321f041078 100644
--- a/lib/dotcom_web/components/live_components/trip_planner_results_section.ex
+++ b/lib/dotcom_web/components/live_components/trip_planner_results_section.ex
@@ -10,7 +10,10 @@ defmodule DotcomWeb.Components.LiveComponents.TripPlannerResultsSection do
 
   @impl true
   def mount(socket) do
-    {:ok, socket |> assign(:expanded_itinerary_index, nil)}
+    {:ok,
+     socket
+     |> assign(:expanded_itinerary_index, nil)
+     |> assign(:selected_itinerary_detail_index, 0)}
   end
 
   @impl true
@@ -64,6 +67,7 @@ defmodule DotcomWeb.Components.LiveComponents.TripPlannerResultsSection do
           <.itinerary_panel
             results={results}
             details_index={@expanded_itinerary_index}
+            selected_itinerary_detail_index={@selected_itinerary_detail_index}
             target={@myself}
           />
         </div>
@@ -117,7 +121,11 @@ defmodule DotcomWeb.Components.LiveComponents.TripPlannerResultsSection do
         <.itinerary_summary summary={@summary} />
       </div>
 
-      <.itinerary_detail :for={itinerary <- @itineraries} itinerary={itinerary} />
+      <.itinerary_detail
+        itineraries={@itineraries}
+        selected_itinerary_detail_index={@selected_itinerary_detail_index}
+        target={@target}
+      />
     </div>
     """
   end
@@ -141,7 +149,17 @@ defmodule DotcomWeb.Components.LiveComponents.TripPlannerResultsSection do
         _ -> nil
       end
 
-    {:noreply, socket |> assign(:expanded_itinerary_index, index)}
+    {:noreply,
+     socket
+     |> assign(:expanded_itinerary_index, index)
+     |> assign(:selected_itinerary_detail_index, 0)}
+  end
+
+  @impl true
+  def handle_event("set_selected_itinerary_detail_index", %{"trip-index" => index_str}, socket) do
+    {index, ""} = Integer.parse(index_str)
+
+    {:noreply, socket |> assign(:selected_itinerary_detail_index, index)}
   end
 
   defp format_datetime_short(datetime) do
diff --git a/lib/dotcom_web/components/trip_planner/itinerary_detail.ex b/lib/dotcom_web/components/trip_planner/itinerary_detail.ex
index ae240f1ce7..0cef0b9786 100644
--- a/lib/dotcom_web/components/trip_planner/itinerary_detail.ex
+++ b/lib/dotcom_web/components/trip_planner/itinerary_detail.ex
@@ -1,14 +1,66 @@
 defmodule DotcomWeb.Components.TripPlanner.ItineraryDetail do
   @moduledoc """
-  A component to render an itinerary in detail..
+  The section of the trip planner page that shows the map and
+  the summary or details panel
   """
+
   use DotcomWeb, :component
 
   import DotcomWeb.Components.TripPlanner.Leg
 
   alias Dotcom.TripPlan.PersonalDetail
 
-  def itinerary_detail(assigns) do
+  def itinerary_detail(
+        %{
+          itineraries: itineraries,
+          selected_itinerary_detail_index: selected_itinerary_detail_index
+        } = assigns
+      ) do
+    assigns =
+      assign(assigns, :selected_itinerary, Enum.at(itineraries, selected_itinerary_detail_index))
+
+    ~H"""
+    <div>
+      <p class="text-sm mb-2 mt-3">Depart at</p>
+      <div class="flex">
+        <.depart_at_button
+          :for={{itinerary, index} <- Enum.with_index(@itineraries)}
+          active={@selected_itinerary_detail_index == index}
+          phx-click="set_selected_itinerary_detail_index"
+          phx-value-trip-index={index}
+          phx-target={@target}
+        >
+          <%= Timex.format!(itinerary.start, "%-I:%M%p", :strftime) %>
+        </.depart_at_button>
+      </div>
+      <.specific_itinerary_detail itinerary={@selected_itinerary} />
+    </div>
+    """
+  end
+
+  attr :active, :boolean
+  attr :rest, :global
+  slot :inner_block
+
+  defp depart_at_button(%{active: active} = assigns) do
+    background_class = if active, do: "bg-brand-primary-lightest", else: "bg-transparent"
+    assigns = assign(assigns, :background_class, background_class)
+
+    ~H"""
+    <button
+      type="button"
+      class={[
+        "border border-brand-primary rounded px-2.5 py-1.5 mr-2 text-brand-primary text-lg",
+        "hover:bg-brand-primary-lightest #{@background_class}"
+      ]}
+      {@rest}
+    >
+      <%= render_slot(@inner_block) %>
+    </button>
+    """
+  end
+
+  defp specific_itinerary_detail(assigns) do
     assigns =
       assign(
         assigns,
@@ -19,11 +71,11 @@ defmodule DotcomWeb.Components.TripPlanner.ItineraryDetail do
       )
 
     ~H"""
-    <details class="mt-4">
-      <summary class="border border-2 border-brand-primary px-3 py-2 flex items-center hover:border-brand-primary-darkest hover:bg-gray-lighter">
+    <div class="mt-4">
+      <div>
         Depart at <%= Timex.format!(@itinerary.start, "%-I:%M%p", :strftime) %>
         <.route_symbol :for={route <- @all_routes} route={route} class="ml-2" />
-      </summary>
+      </div>
       <div :for={leg <- @itinerary.legs}>
         <.leg
           start_time={leg.start}
@@ -35,7 +87,7 @@ defmodule DotcomWeb.Components.TripPlanner.ItineraryDetail do
           realtime_state={leg.realtime_state}
         />
       </div>
-    </details>
+    </div>
     """
   end
 end
diff --git a/test/dotcom_web/live/trip_planner_test.exs b/test/dotcom_web/live/trip_planner_test.exs
index d01b899ebb..2d21d4a3db 100644
--- a/test/dotcom_web/live/trip_planner_test.exs
+++ b/test/dotcom_web/live/trip_planner_test.exs
@@ -4,8 +4,33 @@ defmodule DotcomWeb.Live.TripPlannerTest do
   import Mox
   import Phoenix.LiveViewTest
 
+  alias Test.Support.Factories.TripPlanner.TripPlanner, as: TripPlannerFactory
+
   setup :verify_on_exit!
 
+  defp stub_otp_results(itineraries) do
+    expect(OpenTripPlannerClient.Mock, :plan, fn _ ->
+      {:ok, %OpenTripPlannerClient.Plan{itineraries: itineraries}}
+    end)
+  end
+
+  defp stub_populated_otp_results() do
+    itineraries = TripPlannerFactory.build_list(3, :otp_itinerary)
+
+    stub_otp_results(itineraries)
+  end
+
+  defp update_trip_details(itinerary, trip_id: trip_id, start_time: start_time) do
+    updated_transit_leg =
+      itinerary.legs
+      |> Enum.at(1)
+      |> update_in([:trip, :gtfs_id], fn _ -> "ma_mbta_us:#{trip_id}" end)
+
+    itinerary
+    |> Map.update!(:legs, &List.replace_at(&1, 1, updated_transit_leg))
+    |> Map.put(:start, DateTime.new!(Date.utc_today(), start_time, "America/New_York"))
+  end
+
   test "Preview version behind basic auth", %{conn: conn} do
     conn = get(conn, ~p"/preview/trip-planner")
 
@@ -96,9 +121,7 @@ defmodule DotcomWeb.Live.TripPlannerTest do
         }
       }
 
-      expect(OpenTripPlannerClient.Mock, :plan, fn _ ->
-        {:ok, %OpenTripPlannerClient.Plan{itineraries: []}}
-      end)
+      stub_otp_results([])
 
       {:ok, view, _html} = live(conn, ~p"/preview/trip-planner?#{params}")
 
@@ -115,16 +138,6 @@ defmodule DotcomWeb.Live.TripPlannerTest do
         Test.Support.Factories.Stops.Stop.build(:stop)
       end)
 
-      # Uhhh the OTP factory will generate with any route_type value but our
-      # parsing will break with unexpected route types
-      itineraries =
-        OpenTripPlannerClient.Test.Support.Factory.build_list(3, :itinerary)
-        |> Enum.map(&Test.Support.Factories.TripPlanner.TripPlanner.limit_route_types/1)
-
-      expect(OpenTripPlannerClient.Mock, :plan, fn _ ->
-        {:ok, %OpenTripPlannerClient.Plan{itineraries: itineraries}}
-      end)
-
       %{
         conn:
           put_req_header(
@@ -144,12 +157,16 @@ defmodule DotcomWeb.Live.TripPlannerTest do
     end
 
     test "starts out with no 'View All Options' button", %{conn: conn, params: params} do
+      stub_populated_otp_results()
+
       {:ok, view, _html} = live(conn, ~p"/preview/trip-planner?#{params}")
 
       refute render_async(view) =~ "View All Options"
     end
 
     test "clicking 'Details' button opens details view", %{conn: conn, params: params} do
+      stub_populated_otp_results()
+
       {:ok, view, _html} = live(conn, ~p"/preview/trip-planner?#{params}")
 
       render_async(view)
@@ -162,6 +179,8 @@ defmodule DotcomWeb.Live.TripPlannerTest do
       conn: conn,
       params: params
     } do
+      stub_populated_otp_results()
+
       {:ok, view, _html} = live(conn, ~p"/preview/trip-planner?#{params}")
 
       render_async(view)
@@ -171,5 +190,83 @@ defmodule DotcomWeb.Live.TripPlannerTest do
 
       refute render_async(view) =~ "View All Options"
     end
+
+    test "'Depart At' buttons toggle which itinerary to show", %{
+      conn: conn,
+      params: params
+    } do
+      trip_datetime_1 = Faker.DateTime.forward(2)
+      trip_time_1 = trip_datetime_1 |> DateTime.to_time()
+      trip_id_1 = Faker.UUID.v4()
+
+      trip_datetime_2 = trip_datetime_1 |> DateTime.shift(hour: 1)
+      trip_time_2 = trip_datetime_2 |> DateTime.to_time()
+      trip_time_display_2 = trip_time_2 |> Timex.format!("%-I:%M", :strftime)
+      trip_id_2 = Faker.UUID.v4()
+
+      base_itinerary = TripPlannerFactory.build(:otp_itinerary)
+
+      # Right now, the headsign (which is what we actually want to
+      # show) is not available from OTP client, but we're rendering
+      # the trip ID in its place. Once the headsign is available, we
+      # should update these updates and the assertions below to use
+      # the headsign instead of the trip ID.
+      stub_otp_results([
+        update_trip_details(base_itinerary, trip_id: trip_id_1, start_time: trip_time_1),
+        update_trip_details(base_itinerary, trip_id: trip_id_2, start_time: trip_time_2)
+      ])
+
+      {:ok, view, _html} = live(conn, ~p"/preview/trip-planner?#{params}")
+
+      render_async(view)
+
+      view |> element("button", "Details") |> render_click()
+
+      assert render_async(view) =~ trip_id_1
+      refute render_async(view) =~ trip_id_2
+
+      view |> element("button", trip_time_display_2) |> render_click()
+
+      assert render_async(view) =~ trip_id_2
+      refute render_async(view) =~ trip_id_1
+    end
+
+    test "'Depart At' button state is not preserved when leaving details view", %{
+      conn: conn,
+      params: params
+    } do
+      trip_datetime_1 = Faker.DateTime.forward(2)
+      trip_time_1 = trip_datetime_1 |> DateTime.to_time()
+      trip_id_1 = Faker.UUID.v4()
+
+      trip_datetime_2 = trip_datetime_1 |> DateTime.shift(hour: 1)
+      trip_time_2 = trip_datetime_2 |> DateTime.to_time()
+      trip_time_display_2 = trip_time_2 |> Timex.format!("%-I:%M", :strftime)
+      trip_id_2 = Faker.UUID.v4()
+
+      base_itinerary = TripPlannerFactory.build(:otp_itinerary)
+
+      # Right now, the headsign (which is what we actually want to
+      # show) is not available from OTP client, but we're rendering
+      # the trip ID in its place. Once the headsign is available, we
+      # should update these updates and the assertions below to use
+      # the headsign instead of the trip ID.
+      stub_otp_results([
+        update_trip_details(base_itinerary, trip_id: trip_id_1, start_time: trip_time_1),
+        update_trip_details(base_itinerary, trip_id: trip_id_2, start_time: trip_time_2)
+      ])
+
+      {:ok, view, _html} = live(conn, ~p"/preview/trip-planner?#{params}")
+
+      render_async(view)
+
+      view |> element("button", "Details") |> render_click()
+      view |> element("button", trip_time_display_2) |> render_click()
+      view |> element("button", "View All Options") |> render_click()
+      view |> element("button", "Details") |> render_click()
+
+      assert render_async(view) =~ trip_id_1
+      refute render_async(view) =~ trip_id_2
+    end
   end
 end
diff --git a/test/support/factories/trip_planner/trip_planner.ex b/test/support/factories/trip_planner/trip_planner.ex
index 8c8858cd79..bfcfe75ff6 100644
--- a/test/support/factories/trip_planner/trip_planner.ex
+++ b/test/support/factories/trip_planner/trip_planner.ex
@@ -13,6 +13,11 @@ defmodule Test.Support.Factories.TripPlanner.TripPlanner do
     |> Parser.parse()
   end
 
+  def otp_itinerary_factory do
+    Factory.build(:itinerary)
+    |> limit_route_types()
+  end
+
   def leg_factory do
     [:walking_leg, :transit_leg]
     |> Faker.Util.pick()