In 1758, Cox & Kings became the first travel agency in modern history. In 1840, the Abreu Agency was established in Porto by Bernardo Abreu, becoming the world's first agency to open its services to the public. A Thomas Cook travel agency in the United Kingdom, which ceased operating in 2019.

The title of the "oldest travel agency in the world" is most commonly held by Cox & Kings, which was established on July 21, 1758, when Richard Cox was appointed as the official regimental agent to the British Foot Guards. While it began as a provider of logistical and banking services for the military, it evolved into a modern travel firm over the centuries. Another major contender was Thomas Cook, founded in 1841, which is often credited with inventing the "package holiday" and the role of the modern travel agent; however, the original Thomas Cook group famously collapsed in 2019 (though the brand was later resurrected). For a high-value historical perspective, the Abreu Agency in Portugal (founded 1840) is recognized as the world's oldest agency to open its services to the general public. In 2026, Cox & Kings remains the technical "first" in history, representing a 260-plus-year legacy of managing global logistics and turning the dream of exploration into a professional, commercial industry.