I've traveled around the USA a lot in my life and I've always noticed how many city names are re-used from state-to-state (not to mention US cities that use names from other countries)!

On a trip to Bowling Green, KY a couple of years ago, we accidentally booked a hotel for Bowling Green, OH and I started to wonder: How many unique city names are there?!?

So, today, I decided to try and roughly quantify it. I found this great free database of US cities from SimpleMaps which has 30,844 US cities listed in a convenient CSV format.

I threw together a simple PHP script to process the data and here's what I found.

Out of 30,844 US cities, there were 16,782 cities with unique names (about 54%).

And the most common city names (which I defined as cities that were duplicated 15 times or more) are:

• Franklin (29)
• Fairview (24)
• Marion (23)
• Clinton (23)
• Greenville (22)
• Springfield (21)
• Madison (21)
• Georgetown (20)
• Centerville (20)
• Kingston (20)
• Arlington (19)
• Salem (19)
• Clayton (19)
• Washington (18)
• Dayton (18)
• Oakland (18)
• Lexington (18)
• Princeton (18)
• Waverly (18)
• Cleveland (17)
• Jackson (17)
• Manchester (17)
• Fairfield (17)
• Burlington (17)
• Hillsboro (17)
• Auburn (17)
• Ashland (17)
• Riverside (16)
• Buffalo (16)
• Trenton (16)
• Mount Vernon (16)
• Farmington (16)
• Milton (16)
• Chester (16)
• Jamestown (16)
• Jefferson (16)
• Fulton (16)
• Columbus (15)
• Bridgeport (15)
• Columbia (15)
• Albany (15)
• Aurora (15)
• Henderson (15)
• Monroe (15)
• Utica (15)
• Middletown (15)
• Florence (15)
• Troy (15)
• Lebanon (15)
• Weston (15)
• Hamilton (15)
• Danville (15)
• Liberty (15)
• Oxford (15)
• Newport (15)
• Hudson (15)
• Midway (15)
• Oak Grove (15)
• Union (15)

Here's a Github project which has a basic composer file and docker setup for running locally.

And here's the code for parsing the data:

<?php

require_once __DIR__ . '/vendor/autoload.php';

use League\Csv\Reader;

$csv = Reader::createFromPath(__DIR__ . '/uscities.csv', 'r');
$csv->setHeaderOffset(0);
$header_offset = $csv->getHeaderOffset();
$header = $csv->getHeader(); 

$results = [];

$records = $csv->getRecords();
$cities = [];
foreach ($records as $offset => $record) {
	$cities[] = $record['city_ascii'];
	$clean_name = preg_replace('/[^A-Za-z0-9]/', '', $record['city_ascii']);

	if ( ! isset($results[$clean_name])) {
		$results[$clean_name] = [
			'count' => 0,
			'name' => $record['city_ascii'],
		];
	}

	$results[$clean_name]['count']++;
}

uasort($results, function($a, $b) {
	if ($a['count'] == $b['count']) {
		return 0;
	}

	return $a['count'] > $b['count'] ? -1 : 1;
});

$common_cities = array_filter($results, function($city) {
	return $city['count'] >= 15;
});

$unique_cities = array_filter($results, function($city) {
	return $city['count'] === 1;
});

$unique_city_count = count($unique_cities);
$total_city_count = count($cities);

echo "Total cities: $total_city_count<br />";
echo "Unique cities: $unique_city_count<br />";
echo "Percent unique: " . round($unique_city_count / $total_city_count * 100, 2) . "%<br />";

echo "<br />Common cities:<br />";
foreach ($common_cities as $city) {
	echo $city['name'] . ' (' . $city['count'] . ')<br />';
}