diff --git a/.eslintrc.json b/.eslintrc.json
index ee74712..2797b0d 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -24,7 +24,7 @@
     "import/no-cycle": "error",
     "import/no-duplicates": ["error", { "prefer-inline": true }],
     "import/no-extraneous-dependencies": ["error"],
-    "import/no-internal-modules": ["error", { "allow": ["*/lib/*"] }],
+    "import/no-internal-modules": ["error", { "allow": ["*/lib/*", "world_countries_lists/data/**/*.json"] }],
     "import/no-named-as-default": "off",
     "import/no-named-as-default-member": "off",
     "quotes": ["error", "single", { "avoidEscape": true }]
diff --git a/package-lock.json b/package-lock.json
index 62f740f..b06a80c 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -12,14 +12,17 @@
         "@observablehq/framework": "^1.9.0",
         "d3-dsv": "^3.0.1",
         "d3-time-format": "^4.1.0",
+        "diacritics": "^1.3.0",
         "effect": "^3.3.5",
         "i18n-iso-countries": "^7.11.2",
-        "iso-639-1": "^3.1.2"
+        "iso-639-1": "^3.1.2",
+        "world_countries_lists": "^2.9.0"
       },
       "devDependencies": {
         "@dotenvx/dotenvx": "^1.5.0",
         "@trivago/prettier-plugin-sort-imports": "^4.3.0",
         "@tsconfig/node20": "^20.1.4",
+        "@types/diacritics": "^1.3.3",
         "@types/node": "^20.14.9",
         "@typescript-eslint/eslint-plugin": "^7.14.1",
         "@typescript-eslint/parser": "^7.14.1",
@@ -2018,6 +2021,12 @@
       "integrity": "sha512-sqgsT69YFeLWf5NtJ4Xq/xAF8p4ZQHlmGW74Nu2tD4+g5fAsposc4ZfaaPixVu4y01BEiDCWLRDCvDM5JOsRxg==",
       "dev": true
     },
+    "node_modules/@types/diacritics": {
+      "version": "1.3.3",
+      "resolved": "https://registry.npmjs.org/@types/diacritics/-/diacritics-1.3.3.tgz",
+      "integrity": "sha512-wt0tBItmBsOUVZ8+MCrkBMoVfH/EUZeTXwYSekVVYilZlGDYssREUR+sX72mHvl2IrbdCKgpYARXKh3awD2how==",
+      "dev": true
+    },
     "node_modules/@types/estree": {
       "version": "1.0.5",
       "resolved": "https://registry.npmjs.org/@types/estree/-/estree-1.0.5.tgz",
@@ -8870,6 +8879,11 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/world_countries_lists": {
+      "version": "2.9.0",
+      "resolved": "https://registry.npmjs.org/world_countries_lists/-/world_countries_lists-2.9.0.tgz",
+      "integrity": "sha512-VAS+QcV3khDD120VhFOYx6ntSKHWdigp0+MSwj2wxdAnHpbPnKhDWkLOw8A1zxkMnFmpieG9pp30FW4etwHPWw=="
+    },
     "node_modules/wrap-ansi": {
       "version": "9.0.0",
       "resolved": "https://registry.npmjs.org/wrap-ansi/-/wrap-ansi-9.0.0.tgz",
diff --git a/package.json b/package.json
index fbf9cf2..83b3fff 100644
--- a/package.json
+++ b/package.json
@@ -9,14 +9,17 @@
     "@observablehq/framework": "^1.9.0",
     "d3-dsv": "^3.0.1",
     "d3-time-format": "^4.1.0",
+    "diacritics": "^1.3.0",
     "effect": "^3.3.5",
     "i18n-iso-countries": "^7.11.2",
-    "iso-639-1": "^3.1.2"
+    "iso-639-1": "^3.1.2",
+    "world_countries_lists": "^2.9.0"
   },
   "devDependencies": {
     "@dotenvx/dotenvx": "^1.5.0",
     "@trivago/prettier-plugin-sort-imports": "^4.3.0",
     "@tsconfig/node20": "^20.1.4",
+    "@types/diacritics": "^1.3.3",
     "@types/node": "^20.14.9",
     "@typescript-eslint/eslint-plugin": "^7.14.1",
     "@typescript-eslint/parser": "^7.14.1",
diff --git a/src/lib/Iso3166.ts b/src/lib/Iso3166.ts
index de36d08..4298463 100644
--- a/src/lib/Iso3166.ts
+++ b/src/lib/Iso3166.ts
@@ -1,6 +1,8 @@
 import { Schema } from '@effect/schema'
+import diacritics from 'diacritics'
 import { Array, Option, type Predicate, String, flow } from 'effect'
 import iso3166 from 'i18n-iso-countries'
+import subDivisions from 'world_countries_lists/data/subdivisions/subdivisions.json'
 
 export type Alpha2Code = iso3166.Alpha2Code
 
@@ -14,6 +16,18 @@ export const guessCountry: (location: string) => Option.Option<Alpha2Code> = flo
   String.replaceAll(/\((.+?)\)/g, ', $1'),
   String.replaceAll(/( and | - )/gi, ', '),
   location => Array.prepend(Array.map(location.split(',').reverse(), String.trim), location),
-  Array.findFirst(Option.liftNullable(location => iso3166.getAlpha2Code(location, 'en'))),
+  Array.findFirst(location =>
+    Option.fromNullable(iso3166.getAlpha2Code(location, 'en')).pipe(
+      Option.orElse(() =>
+        Option.map(
+          Array.findFirst(
+            subDivisions,
+            subDivision => diacritics.remove(location).toLowerCase() === subDivision.name.toLowerCase(),
+          ),
+          subDivision => subDivision.country,
+        ),
+      ),
+    ),
+  ),
   Option.filter(isAlpha2Code),
 )
diff --git a/test/Iso3166.test.ts b/test/Iso3166.test.ts
index b0d8cef..002ffe8 100644
--- a/test/Iso3166.test.ts
+++ b/test/Iso3166.test.ts
@@ -5,18 +5,23 @@ import * as _ from '../src/lib/Iso3166.js'
 describe('guessCountry', () => {
   test.for([
     ['Algiers ( Algeria)', 'DZ'],
+    ['Baylor College of Medicine, Houston, Texas', 'US'],
     ['Chicago, IL, USA', 'US'],
     ['Colorado - United States', 'US'],
     ['Czech Republic', 'CZ'],
     ['Czechia', 'CZ'],
     ['GHANA', 'GH'],
+    ['London, Ontario', 'CA'],
     ['London, UK', 'GB'],
     ['London, United Kingdom', 'GB'],
+    ['Québec', 'CA'],
     ['Rio de Janeiro, Brazil.', 'BR'],
+    ['Sunnyvale, California', 'US'],
     ['UK', 'GB'],
     ['U.K.', 'GB'],
     ['United Kingdom', 'GB'],
     ['united states', 'US'],
+    ['Washington, DC', 'US'],
   ])('guesses %s', ([input, expected]) => {
     const actual = _.guessCountry(input)
 
@@ -24,18 +29,13 @@ describe('guessCountry', () => {
   })
 
   test.for([
-    'Baylor College of Medicine, Houston, Texas',
     'Beijing University of Technology, Beijing 100124, PR China',
     'Fayetteville GA (near Atlanta)',
     'London',
-    'London, Ontario',
     'Mars',
     'New York City and Los Angeles',
-    'Québec',
     'Southeast Asia',
-    'Sunnyvale, California',
     'The UK',
-    'Washington, DC',
   ])("doesn't guess %s", input => {
     const actual = _.guessCountry(input)
 
diff --git a/tsconfig.json b/tsconfig.json
index 923b79b..7410bb5 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,7 +1,8 @@
 {
   "extends": "@tsconfig/node20/tsconfig.json",
   "compilerOptions": {
-    "exactOptionalPropertyTypes": true
+    "exactOptionalPropertyTypes": true,
+    "resolveJsonModule": true
   },
   "include": ["src", "test", "*.ts"]
 }