The history of colonization on the California Coast spans three nations: Spain, independent Mexico, and eventually, the United States. Perhaps nowhere is this seen so clearly as in Monterey, California’s original capital. The Old Custom House is a National Historic Landmark that stands as a reminder of the city’s Mexican heritage and Mexico's political presence in the city during the mid-1800s. The landmark and its surrounding historic district are a living museum that interprets the rich early story of Monterey and the economic foundations of California.

Before the Spanish began to explore and colonize the region, the Ohlone populated the Monterey area. The coastal lands were flush with natural resources, fertile soil, and a temperate climate – all qualities that would later attract the Spaniards.
In 1542, Spanish explorer Juan Rodríquez Cabrillo was the first non-Native person to see the wide Monterey Bay. In 1770, Captain Gaspar de Portolá and Franciscan Father Junipero Serra established the Royal Presidio of Monterey and the San Carlos de Borromeo Mission – the city’s first permanent buildings. The presidio was soon serving as the seat of the Spanish government in the area. By 1776, Monterey became the capital of both Baja (lower) and Alta (upper) California.
Monterey thrived, mainly within the protective walls of the military presidio, until Argentinean revolutionary privateer Hipolito Bouchard attacked the city in 1818. The conflict would be the only land and sea battle fought on the West Coast. Bouchard sacked the town leaving severe damage in his wake. Over the next decade Monterey remained the capital and slowly rebuilt. Residences and businesses moved beyond the presidio’s walls and the street pattern still visible in Monterey today began to develop.
The Custom House in Monterey emerged out of this new period of prosperity. In April of 1822, the city learned that Mexico had won independence from Spanish rule the year before. California immediately pledged allegiance to the Mexican government. While Spain had prohibited international trade in its territories, the Mexican government opened its borders and seaports to foreign trade. The purpose of the Custom House was to collect duties on foreign goods at the bay, California’s main point of entry.
Constructed in 1827 and perched on the wide bay at Monterey, the Old Custom House was the first government building in California and the earliest government building on the west coast. The building quickly became critical to trade and cargo sales during the Mexican Era. A wide variety of goods began to flow into California, arriving on ships from American, British, and South American markets. A single vessel involved in California’s popular hide and tallow trade might owe $5,000 to $25,000 in duty fees on just one cargo load. The collection of customs fees was California’s most important source of revenue during the 19th century.
The growing trade through Monterey launched the city into a new era of heightened prosperity. What had begun as a small presidio grew into a major cosmopolitan community and an attractive destination for American travelers. This growing American presence in 1842 led to greater interest by the United States government in the territory, and by 1844, the United States established an American consulate in Monterey.
Thomas O. Larkin, a New England merchant who came to California in April 1832, was the first and only United States Consul to Mexican-ruled California. When Larkin first moved to Monterey, he quickly became an affluent citizen and developed a successful trading business. Because of his knowledge and position, Secretary of State Buchanan appointed him as Consul. Larkin is considered to be a key player in the eventual annexation of California by the United States. Larkin's home served as the consulate from 1844 to 1846 and is now listed in the National Register of Historic Places.
Larkin altered and expanded the single-story Custom House. By 1846, the custom house had reached its present form and had two stories, a two-story porch veranda, four large contiguous rooms, and a tiled hipped roof. At this same time, Mexico and the United States went to war. Commodore John D. Sloat, commander of the U.S. Pacific squadron, arrived in Monterey during the “Bear Flag Revolt.” He raised the American flag over the Custom House and claimed California as U.S. territory.
The Old Custom House was the American-operated custom house until 1868 and became a private residence. By the early 1890s, the building was unoccupied and began to deteriorate. In 1900, it became one of California’s earliest preservation projects. The Native Sons of the Golden West completed the original restoration efforts by 1917. In 1929, the building became the first California State Landmark. On January 1, 1930, the State Division of Beaches and Parks took it over and opened it to the public as a museum. In 1960, the Custom House was designated a National Historic Landmark and remains in use as a museum and visitor center.
Visitors to the Old Custom House can tour the building and peruse historical objects and educational materials. The building sits within the Monterey Old Town Historic District, itself a National Historic Landmark. The district showcases several dozen 19th-century adobe buildings from both the Spanish and Mexican eras that at one time were the hub of California's social, economic, and political activities. The district is also part of California’s Monterey State Historic Park.