diff --git a/data/CONTRIBUTING.md b/data/CONTRIBUTING.md
index 74444fc..50e2e59 100644
--- a/data/CONTRIBUTING.md
+++ b/data/CONTRIBUTING.md
@@ -37,6 +37,7 @@ below is also machine-enforced by [`places.schema.json`](places.schema.json), wh
 **Fields:**
 - `id`: `<city-prefix>-<type>-<number>`. Prefix is a short slug for the city (e.g. `mum`, `thane`, `navi`, `ldn`, `jkt`). Increment from the highest existing number in the file for that prefix.
 - `city`: lowercase, underscore-separated slug (e.g. `mumbai`, `navi_mumbai`, `jakarta`). Any city worldwide is welcome, not just Mumbai/Thane/Navi Mumbai.
+- `country`: optional for now. The place's ISO 3166-1 alpha-2 country code in capitals (e.g. `IN`, `GB`, `KE`), the same codes competitions use. Lowercase or a country name fails `npm run validate`. Existing records are being backfilled, after which it becomes required (#288).
 - `type`: must match the filename exactly
 - `lat`/`lng`: from Google Maps (right-click pin, "What's here?"). Any real-world coordinate works: `places.schema.json` checks latitude is between -90 and 90 and longitude between -180 and 180.
 - `address`: optional, short, human-readable
diff --git a/data/places.schema.json b/data/places.schema.json
index 288e32f..fed19d5 100644
--- a/data/places.schema.json
+++ b/data/places.schema.json
@@ -27,6 +27,11 @@
       "pattern": "^[a-z0-9]+(_[a-z0-9]+)*$",
       "description": "Lowercase, underscore-separated slug, e.g. \"mumbai\", \"navi_mumbai\". Any city worldwide is welcome, not a fixed enum."
     },
+    "country": {
+      "type": "string",
+      "pattern": "^[A-Z]{2}$",
+      "description": "Optional for now. ISO 3166-1 alpha-2 country code in capitals, e.g. \"IN\", \"GB\". Competitions already use the same codes."
+    },
     "lat": {
       "type": "number",
       "minimum": -90,
diff --git a/scripts/lib/data-validation.mjs b/scripts/lib/data-validation.mjs
index 0674755..09fa679 100644
--- a/scripts/lib/data-validation.mjs
+++ b/scripts/lib/data-validation.mjs
@@ -69,3 +69,8 @@ export class Reporter {
     this.totalWarnings++;
   }
 }
+
+/** True when `value` is an ISO 3166-1 alpha-2 style country code: exactly two capital letters. */
+export function isCountryCode(value) {
+  return typeof value === "string" && /^[A-Z]{2}$/.test(value);
+}
diff --git a/scripts/validate-places.mjs b/scripts/validate-places.mjs
index 59d1d61..8bfc632 100644
--- a/scripts/validate-places.mjs
+++ b/scripts/validate-places.mjs
@@ -11,6 +11,7 @@
  *   - type is one of the schema's enum values
  *   - type matches the filename it lives in
  *   - city is a lowercase, underscore-separated slug
+ *   - country, when present, is a two-letter upper-case ISO 3166-1 code
  *   - id matches the <city-prefix>-<type>-<number> convention, or is a bare
  *     numeric id (the College Board SAT centre code convention)
  *   - lat/lng are numbers within the schema's min/max bounds
@@ -29,6 +30,7 @@ import { fileURLToPath } from "url";
 import {
   Reporter,
   hasEmDash,
+  isCountryCode,
   isLatLngPlaceholderGmapsLink,
   isRealIsoDate,
 } from "./lib/data-validation.mjs";
@@ -173,6 +175,14 @@ for (const file of files) {
       );
     }
 
+    // country, when present, is an upper-case ISO 3166-1 alpha-2 code (see #288)
+    if (r.country !== undefined && !isCountryCode(r.country)) {
+      err(
+        loc,
+        `country must be a two-letter upper-case ISO 3166-1 alpha-2 code like "IN", got ${JSON.stringify(r.country)}`,
+      );
+    }
+
     // valid_till format, when present
     if (r.valid_till !== undefined && !isRealIsoDate(r.valid_till)) {
       err(loc, `valid_till must be a real ISO date (YYYY-MM-DD), got "${r.valid_till}"`);
diff --git a/src/lib/country-code.test.ts b/src/lib/country-code.test.ts
new file mode 100644
index 0000000..66faf14
--- /dev/null
+++ b/src/lib/country-code.test.ts
@@ -0,0 +1,27 @@
+import { describe, expect, it } from "vitest";
+
+import { isCountryCode } from "../../scripts/lib/data-validation.mjs";
+
+describe("isCountryCode", () => {
+  it("accepts two capital letters", () => {
+    for (const code of ["IN", "GB", "KE", "US"]) expect(isCountryCode(code)).toBe(true);
+  });
+
+  it("rejects names, lower case, wrong length and non-strings", () => {
+    for (const value of [
+      "india",
+      "in",
+      "In",
+      "IND",
+      "I",
+      "",
+      "I1",
+      "I N",
+      undefined,
+      null,
+      7,
+    ]) {
+      expect(isCountryCode(value), String(value)).toBe(false);
+    }
+  });
+});
diff --git a/src/lib/types.ts b/src/lib/types.ts
index 9e7e694..7ea2969 100644
--- a/src/lib/types.ts
+++ b/src/lib/types.ts
@@ -280,6 +280,8 @@ export interface Place {
   name: string;
   type: PlaceType;
   city: City;
+  /** ISO 3166-1 alpha-2 country code in capitals (e.g. "IN"). Optional while records are backfilled (#288). */
+  country?: string;
   lat: number;
   lng: number;
   address?: string;