diff --git a/CHANGELOG.md b/CHANGELOG.md
index c3ce393c..1add4c0a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,20 +5,18 @@
 - Country-independent traffic sign enum
 - Missing country-specific max speed sign IDs
 - Automatically generated TrafficSignIDCountries enum for importing in other scripts
-
-### Added
 - GroundTruthPredictor class to use stored trajectories as prediction
-
-### Changed
-- Optimization-based planner tutorial now uses planner and predictor interfaces
+- Function to append a state to a trajectory
 
 ### Fixed
 - Typo: `TrafficSigInterpreter` → `TrafficSignInterpreter`
 - Typo EMERGENCY_STOP traffic sign enum name
 
 ### Changed
+- Optimization-based planner tutorial now uses planner and predictor interfaces
 - Simplified traffic sign matching in FileReader
 - The occupancy set, initial time step ,and final time step are now computed properties of TrajectoryPrediction
+- Trajectory now allows direct access to the state list
 
 ### Removed
 - Setters for initial and final time step in predictions
diff --git a/commonroad/scenario/trajectory.py b/commonroad/scenario/trajectory.py
index a476c217..da2dd29f 100644
--- a/commonroad/scenario/trajectory.py
+++ b/commonroad/scenario/trajectory.py
@@ -1,5 +1,5 @@
 import warnings
-from typing import List, Tuple, Union
+from typing import List, Union
 
 import numpy as np
 
@@ -35,7 +35,7 @@ def __init__(self, initial_time_step: int, state_list: List[TraceState]):
         """
         self.initial_time_step: int = initial_time_step
 
-        self._state_list: Tuple[TraceState] = tuple(self.check_state_list(state_list))
+        self._state_list: List[TraceState] = self.check_state_list(state_list)
 
     def check_state_list(self, state_list: List[TraceState]) -> List[TraceState]:
         """
@@ -79,7 +79,7 @@ def __eq__(self, other):
         return self._initial_time_step == other.initial_time_step and list(self._state_list) == list(other.state_list)
 
     def __hash__(self):
-        return hash((self._initial_time_step, self._state_list))
+        return hash((self._initial_time_step, tuple(self._state_list)))
 
     @property
     def initial_time_step(self) -> int:
@@ -94,10 +94,36 @@ def initial_time_step(self, initial_time_step):
         )
         self._initial_time_step = initial_time_step
 
+    def append_state(self, state: TraceState):
+        """Append the state to the trajectory.
+
+        :param state: The new state. It's time step must be larger than the time step of the last state in the trajectory
+        """
+        assert isinstance(
+            state, State
+        ), "<Trajectory/append_state>: argument state of wrong type. Expected type: %s. Got type: %s." % (
+            State,
+            type(state),
+        )
+        assert set(self._state_list[0].used_attributes) == set(state.used_attributes), (
+            "<Trajectory/append_state>: attributes of the argument state do not match"
+            " the attributes of the other states in the state list."
+            " Expected attributes: '%s'. Got attributes: '%s'" % (self._state_list[0].attributes, state.attributes)
+        )
+
+        assert state.time_step > self.final_state.time_step, (
+            "<Trajectory/append_state>: the time step of the argument state"
+            " must be larger than the time step of the last state in the trajectory."
+            " Time step of last state in trajectory: %s. Got time step: %s"
+            % (self.final_state.time_step, state.time_step)
+        )
+
+        self._state_list.append(state)
+
     @property
     def state_list(self) -> List[TraceState]:
         """List of states of the trajectory over time."""
-        return list(self._state_list)
+        return self._state_list
 
     @property
     def final_state(self) -> TraceState:
@@ -147,7 +173,7 @@ def translate_rotate(self, translation: np.ndarray, angle: float):
         new_state_list = []
         for i in range(len(self._state_list)):
             new_state_list.append(self._state_list[i].translate_rotate(translation, angle))
-        self._state_list = tuple(new_state_list)
+        self._state_list = new_state_list
 
     @classmethod
     def resample_continuous_time_state_list(
diff --git a/tests/scenario/test_trajectory.py b/tests/scenario/test_trajectory.py
index ec8e1891..c69d61e8 100644
--- a/tests/scenario/test_trajectory.py
+++ b/tests/scenario/test_trajectory.py
@@ -3,7 +3,7 @@
 import numpy as np
 
 from commonroad.common.util import Interval
-from commonroad.scenario.state import KSState
+from commonroad.scenario.state import InitialState, KSState
 from commonroad.scenario.trajectory import Trajectory
 
 
@@ -156,6 +156,26 @@ def test_check_state_list(self):
             ],
         )
 
+    def test_append_state(self):
+        states = list()
+        states.append(KSState(position=np.array([1.35, -2.4]), orientation=0.87, time_step=5))
+        trajectory = Trajectory(5, states)
+        self.assertRaises(AssertionError, trajectory.append_state, None)
+        self.assertRaises(
+            AssertionError,
+            trajectory.append_state,
+            InitialState(time_step=6, position=np.array([1.0, -2.0]), orientation=0.5, velocity=3.3, acceleration=1.3),
+        )
+        self.assertRaises(
+            AssertionError,
+            trajectory.append_state,
+            KSState(position=np.array([1.0, -2.0]), orientation=0.8, time_step=0),
+        )
+
+        new_state = KSState(position=np.array([2.0, -3.0]), orientation=0.9, time_step=6)
+        trajectory.append_state(new_state)
+        self.assertEqual(trajectory.state_at_time_step(6), new_state)
+
 
 if __name__ == "__main__":
     unittest.main()