diff --git a/js/AxisLine.js b/js/AxisLine.js
index 8fac508..5d0c225 100644
--- a/js/AxisLine.js
+++ b/js/AxisLine.js
@@ -1,4 +1,4 @@
-// Copyright 2020, University of Colorado Boulder
+// Copyright 2020-2021, University of Colorado Boulder
 
 /**
  * AxisLine is an axis that consists of a line, with no arrow heads.
diff --git a/js/AxisNode.js b/js/AxisNode.js
index c104908..40ada6b 100644
--- a/js/AxisNode.js
+++ b/js/AxisNode.js
@@ -1,4 +1,4 @@
-// Copyright 2020, University of Colorado Boulder
+// Copyright 2020-2021, University of Colorado Boulder
 
 /**
  * Shows a line that depicts an axis.  This is typically bolder than any grid line (if any), and typically at x=0 or