Map - Humacao, Puerto Rico (Humacao Municipio)

Humacao is a city and municipality in Puerto Rico located in the eastern coast of the island, north of Yabucoa; south of Naguabo; east of Las Piedras; and west of Vieques Passage. Humacao is spread over 12 barrios and Humacao Pueblo (the downtown area and the administrative center of the city). It is part of the San Juan-Caguas-Guaynabo Metropolitan Statistical Area.

The region of what is now Humacao belonged to the Taíno region of Humaka, which covered a portion of the southeast coast of Puerto Rico. The region was led by cacique Jumacao (also referred to as "Macao"). The Taíno settlement was located on the shores of what is called now the Humacao River. It is believed that the Taíno chief Jumacao was the first "cacique" to learn to read and write in Spanish, since he wrote a letter to the King of Spain Charles I complaining about how the Governor of the island wasn't complying with their peace agreement. In the letter, Jumacao argued that their people were virtually prisoners of Spain. It is said that King Charles was so moved by the letter that he ordered the Governor to obey the terms of the treaty.

During the early 16th century, the region was populated by cattle ranchers. However, since most of them officially resided in San Juan, a settlement was never officially organized. At the beginning of the 18th century, specifically around 1721–1722, the first official settlement was constituted in the area. Most of the residents at the time were immigrants from the Canary Islands, but due to attacks from Caribs, pirates, and other settlers, some of them moved farther into the island in what is now Las Piedras. Still, some settlers remained and by 1776, historian Fray Íñigo Abbad y Lasierra visited the area and wrote about the population there. By 1793, the church was recognized as parish and the settlement was officially recognized as town.

By 1894, Humacao was recognized as a city. Due to its thriving population, buildings and structures like a hospital, a theater, and a prison were built in the city. In 1899, after the United States invasion of the island as a result of the Spanish–American War, the municipality of Las Piedras was annexed to Humacao. This lasted until 1914, when the Legislative Assembly of Puerto Rico voted on splitting both towns again.

Puerto Rico was ceded by Spain in the aftermath of the Spanish–American War under the terms of the Treaty of Paris of 1898 and became a territory of the United States. In 1899, the United States Department of War conducted a census of Puerto Rico finding that the population of Humacao was 14,313.

Humacao was led by mayor Marcelo Trujillo Panisse for over a decade. A basketball star in his early years, Trujillo has pushed for the development of infrastructure facilities for sports and the fine arts in the city. In March 2008, a new Roman Catholic diocese was established as the Fajardo-Humacao diocese. Its first bishop is Monsignor Eusebio 'Chebito' Ramos Morales, a maunabeño who was rector of the Humacao's main parish in the 1990s.

In 2019, Luis Raul Sanchez became interim mayor of Humacao after Marcelo Trujillo Panisse died in September 2019.

On September 20, 2017 Hurricane Maria struck Puerto Rico. Punta Santiago in Humacao saw a six-foot storm surge. The hurricane caused destruction of homes and infrastructure.