diff --git a/.golangci.yml b/.golangci.yml
index 1bd7b68a..09b52815 100644
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -113,13 +113,14 @@ linters:
       - linters:
           - noctx
         path: _test\.go
-      # misspell: "cancelled" is the canonical stored status value in
-      # pkg/ladder (RunStatusCancelled, TrancheStatusCancelled); allow the UK
-      # spelling in the files that carry it.
+      # misspell: pkg/ladder writes "canceled" but still reads the legacy
+      # "cancelled" that rows carried before #554, and keeps the deprecated
+      # RunStatusCancelled/TrancheStatusCancelled aliases; allow the UK spelling
+      # in the files that carry it.
       - linters:
           - misspell
-        path: pkg/ladder/(store|types_test)\.go
-        text: "cancelled"
+        path: pkg/ladder/(store|types_test|canceled_spelling_test)\.go
+        text: "(?i)cancelled"
     paths:
       - third_party$
       - builtin$
diff --git a/CHANGELOG.md b/CHANGELOG.md
index f5b6c14b..bdb07c9d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -191,6 +191,13 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/).
   `cache.PurchaseCommitment` now refuses before any API call with an error
   wrapping `common.ErrRefusedBeforePurchase`. Consumers that buy an Azure
   `ServiceCache` recommendation must route it to managedredis (#538).
+- Ladder run and tranche statuses now write the US spelling `canceled`
+  (`RunStatusCanceled`, `TrancheStatusCanceled`). Rows holding the legacy
+  `cancelled` still validate, count as terminal, and parse to the new
+  constants through `ParseRunStatus` and `ParseTrancheStatus`. The
+  `RunStatusCancelled` and `TrancheStatusCancelled` names remain as
+  deprecated aliases with the new value. Consumers that compare raw stored
+  strings or filter on `cancelled` in SQL must accept both spellings.
 - `ListTargetOfferings` now walks up to 50 pages (about 5000 offerings)
   instead of 10, and returns an error wrapping the new
   `ec2.ErrTargetOfferingsTruncated` (with no list) when that bound is hit,
diff --git a/pkg/ladder/canceled_spelling_test.go b/pkg/ladder/canceled_spelling_test.go
new file mode 100644
index 00000000..804521d1
--- /dev/null
+++ b/pkg/ladder/canceled_spelling_test.go
@@ -0,0 +1,42 @@
+package ladder
+
+import "testing"
+
+// #554: writers emit the US spelling "canceled"; rows written before keep the
+// legacy "cancelled" and still parse, validate and count as terminal.
+
+func TestCanceledStatuses_WriteTheUSSpelling(t *testing.T) {
+	t.Parallel()
+	if RunStatusCanceled != "canceled" || TrancheStatusCanceled != "canceled" {
+		t.Fatalf("writers must emit \"canceled\": run %q, tranche %q", RunStatusCanceled, TrancheStatusCanceled)
+	}
+	if RunStatusCancelled != RunStatusCanceled || TrancheStatusCancelled != TrancheStatusCanceled {
+		t.Fatal("the deprecated Cancelled aliases must equal the Canceled constants")
+	}
+}
+
+func TestCanceledStatuses_LegacySpellingParsesToCanceled(t *testing.T) {
+	t.Parallel()
+	for _, in := range []string{"canceled", "cancelled"} {
+		run, err := ParseRunStatus(in)
+		if err != nil || run != RunStatusCanceled {
+			t.Errorf("ParseRunStatus(%q) = %q, %v; want %q", in, run, err, RunStatusCanceled)
+		}
+		tr, err := ParseTrancheStatus(in)
+		if err != nil || tr != TrancheStatusCanceled {
+			t.Errorf("ParseTrancheStatus(%q) = %q, %v; want %q", in, tr, err, TrancheStatusCanceled)
+		}
+		if err := RunStatus(in).Validate(); err != nil {
+			t.Errorf("RunStatus(%q).Validate() = %v; a stored legacy row must still validate", in, err)
+		}
+		if err := TrancheStatus(in).Validate(); err != nil {
+			t.Errorf("TrancheStatus(%q).Validate() = %v", in, err)
+		}
+		if !RunStatus(in).IsTerminal() {
+			t.Errorf("RunStatus(%q).IsTerminal() = false", in)
+		}
+		if TrancheStatus(in).allowsFiredAt() {
+			t.Errorf("TrancheStatus(%q) must not allow FiredAt", in)
+		}
+	}
+}
diff --git a/pkg/ladder/store.go b/pkg/ladder/store.go
index e9227c48..48234e34 100644
--- a/pkg/ladder/store.go
+++ b/pkg/ladder/store.go
@@ -17,8 +17,16 @@ const (
 	RunStatusExecuting        RunStatus = "executing"
 	RunStatusCompleted        RunStatus = "completed"
 	RunStatusFailed           RunStatus = "failed"
-	RunStatusCancelled        RunStatus = "cancelled"
+	RunStatusCanceled         RunStatus = "canceled"
 	RunStatusExpired          RunStatus = "expired"
+
+	// Deprecated: use RunStatusCanceled. Kept so existing callers compile; it
+	// writes the new spelling.
+	RunStatusCancelled = RunStatusCanceled
+
+	// runStatusLegacyCancelled is the spelling rows carried before #554. It is
+	// read, never written.
+	runStatusLegacyCancelled RunStatus = "cancelled"
 )
 
 // Validate returns an error when s is not a recognized RunStatus.
@@ -26,31 +34,35 @@ func (s RunStatus) Validate() error {
 	switch s {
 	case RunStatusPlanned, RunStatusAwaitingApproval, RunStatusApproved,
 		RunStatusExecuting, RunStatusCompleted, RunStatusFailed,
-		RunStatusCancelled, RunStatusExpired:
+		RunStatusCanceled, runStatusLegacyCancelled, RunStatusExpired:
 		return nil
 	}
 	return fmt.Errorf("unknown run status %q", s)
 }
 
 // IsTerminal reports whether s is a terminal run status: RunStatusCompleted,
-// RunStatusFailed, RunStatusCancelled, or RunStatusExpired. Terminal runs are
+// RunStatusFailed, RunStatusCanceled (either spelling), or RunStatusExpired. Terminal runs are
 // the only ones allowed to carry a CompletedAt timestamp (see
 // RunRecord.Validate).
 func (s RunStatus) IsTerminal() bool {
 	switch s {
-	case RunStatusCompleted, RunStatusFailed, RunStatusCancelled, RunStatusExpired:
+	case RunStatusCompleted, RunStatusFailed, RunStatusCanceled, runStatusLegacyCancelled, RunStatusExpired:
 		return true
 	}
 	return false
 }
 
 // ParseRunStatus converts s into a RunStatus, returning a descriptive error
-// when s is not a recognized value.
+// when s is not a recognized value. The legacy "cancelled" reads as
+// RunStatusCanceled.
 func ParseRunStatus(s string) (RunStatus, error) {
 	st := RunStatus(s)
 	if err := st.Validate(); err != nil {
 		return "", err
 	}
+	if st == runStatusLegacyCancelled {
+		return RunStatusCanceled, nil
+	}
 	return st, nil
 }
 
@@ -61,15 +73,23 @@ const (
 	TrancheStatusScheduled TrancheStatus = "scheduled"
 	TrancheStatusFired     TrancheStatus = "fired"
 	TrancheStatusCompleted TrancheStatus = "completed"
-	TrancheStatusCancelled TrancheStatus = "cancelled"
+	TrancheStatusCanceled  TrancheStatus = "canceled"
 	TrancheStatusFailed    TrancheStatus = "failed"
+
+	// Deprecated: use TrancheStatusCanceled. Kept so existing callers compile;
+	// it writes the new spelling.
+	TrancheStatusCancelled = TrancheStatusCanceled
+
+	// trancheStatusLegacyCancelled is the spelling rows carried before #554.
+	// It is read, never written.
+	trancheStatusLegacyCancelled TrancheStatus = "cancelled"
 )
 
 // Validate returns an error when s is not a recognized TrancheStatus.
 func (s TrancheStatus) Validate() error {
 	switch s {
 	case TrancheStatusScheduled, TrancheStatusFired, TrancheStatusCompleted,
-		TrancheStatusCancelled, TrancheStatusFailed:
+		TrancheStatusCanceled, trancheStatusLegacyCancelled, TrancheStatusFailed:
 		return nil
 	}
 	return fmt.Errorf("unknown tranche status %q", s)
@@ -88,12 +108,16 @@ func (s TrancheStatus) allowsFiredAt() bool {
 }
 
 // ParseTrancheStatus converts s into a TrancheStatus, returning a
-// descriptive error when s is not a recognized value.
+// descriptive error when s is not a recognized value. The legacy "cancelled"
+// reads as TrancheStatusCanceled.
 func ParseTrancheStatus(s string) (TrancheStatus, error) {
 	st := TrancheStatus(s)
 	if err := st.Validate(); err != nil {
 		return "", err
 	}
+	if st == trancheStatusLegacyCancelled {
+		return TrancheStatusCanceled, nil
+	}
 	return st, nil
 }
 
diff --git a/pkg/ladder/store_test.go b/pkg/ladder/store_test.go
index d039a6fc..d0111dbd 100644
--- a/pkg/ladder/store_test.go
+++ b/pkg/ladder/store_test.go
@@ -19,7 +19,7 @@ func TestRunStatusIsTerminal(t *testing.T) {
 		{RunStatusExecuting, false},
 		{RunStatusCompleted, true},
 		{RunStatusFailed, true},
-		{RunStatusCancelled, true},
+		{RunStatusCanceled, true},
 		{RunStatusExpired, true},
 	}
 	for _, c := range cases {
@@ -86,9 +86,9 @@ func TestRunRecordValidate(t *testing.T) {
 			wantErr: false,
 		},
 		{
-			name: "RunStatusCancelled with CompletedAt is valid",
+			name: "RunStatusCanceled with CompletedAt is valid",
 			mutate: func(r *RunRecord) {
-				r.Status = RunStatusCancelled
+				r.Status = RunStatusCanceled
 				r.CompletedAt = &now
 			},
 			wantErr: false,
@@ -229,9 +229,9 @@ func TestTrancheValidate(t *testing.T) {
 			wantErr: true,
 		},
 		{
-			name: "TrancheStatusCancelled with FiredAt is invalid",
+			name: "TrancheStatusCanceled with FiredAt is invalid",
 			mutate: func(tr *Tranche) {
-				tr.Status = TrancheStatusCancelled
+				tr.Status = TrancheStatusCanceled
 				tr.FiredAt = &now
 			},
 			wantErr: true,
diff --git a/pkg/ladder/types_test.go b/pkg/ladder/types_test.go
index 9aa145e4..4632ccc1 100644
--- a/pkg/ladder/types_test.go
+++ b/pkg/ladder/types_test.go
@@ -175,7 +175,7 @@ func TestRunStatusValidate(t *testing.T) {
 		{RunStatusExecuting, false},
 		{RunStatusCompleted, false},
 		{RunStatusFailed, false},
-		{RunStatusCancelled, false},
+		{RunStatusCanceled, false},
 		{RunStatusExpired, false},
 		{"unknown-status", true},
 		{"", true},
@@ -200,7 +200,7 @@ func TestTrancheStatusValidate(t *testing.T) {
 		{TrancheStatusScheduled, false},
 		{TrancheStatusFired, false},
 		{TrancheStatusCompleted, false},
-		{TrancheStatusCancelled, false},
+		{TrancheStatusCanceled, false},
 		{TrancheStatusFailed, false},
 		{"unknown-tranche-status", true},
 		{"", true},
@@ -490,7 +490,8 @@ func TestParseRunStatus(t *testing.T) {
 		{"executing", RunStatusExecuting, false},
 		{"completed", RunStatusCompleted, false},
 		{"failed", RunStatusFailed, false},
-		{"cancelled", RunStatusCancelled, false},
+		{"canceled", RunStatusCanceled, false},
+		{"cancelled", RunStatusCanceled, false}, // legacy rows read as canceled (#554)
 		{"expired", RunStatusExpired, false},
 		{"bogus", "", true},
 		{"", "", true},
@@ -523,7 +524,8 @@ func TestParseTrancheStatus(t *testing.T) {
 		{"scheduled", TrancheStatusScheduled, false},
 		{"fired", TrancheStatusFired, false},
 		{"completed", TrancheStatusCompleted, false},
-		{"cancelled", TrancheStatusCancelled, false},
+		{"canceled", TrancheStatusCanceled, false},
+		{"cancelled", TrancheStatusCanceled, false}, // legacy rows read as canceled (#554)
 		{"failed", TrancheStatusFailed, false},
 		{"bogus", "", true},
 		{"", "", true},