Question: When did the 50th state to join the U.S. become part of the country?

full_context: Document 1: 51st state: Before Alaska and Hawaii became states of the United States in 1959, the corresponding expression was ``the 49th state ''.
Document 2: Hawaii: Hawaii (English: / həˈwaɪ. i, - ji, - ʔi / (listen) hə - WY - (y) ee; Hawaiian: Hawai ʻi (həˈvɐjʔi)) is the 50th and most recent state to have joined the United States of America, having received statehood on August 21, 1959. Hawaii is the only U.S. state located in Oceania and the only one composed entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean. Hawaii is the only U.S. state located outside North America.
Document 3: Republic of Cuba (1902–1959): After the Spanish -- American War, Spain and the United States signed the Treaty of Paris (1898), by which Spain ceded Puerto Rico, the Philippines, and Guam to the United States for the sum of $20 million. Cuba gained formal independence from the U.S. on May 20, 1902, as the Republic of Cuba. Under Cuba's new constitution, the U.S. retained the right to intervene in Cuban affairs and to supervise its finances and foreign relations. Under the Platt Amendment, the U.S. leased the Guantánamo Bay naval base from Cuba.
Document 4: Interstate H-1: Interstate H-1 (abbreviated H-1) is the longest and busiest Interstate Highway in the US state of Hawaii. The highway is located on the island of O‘ahu. Despite the number, this is an east–west highway; the 'H'-series (for Hawaii) numbering reflects the order in which routes were funded and built. H-1 goes from Route 93 (Farrington Highway) in Kapolei to Route 72 (Kalanianaole Highway) in Kāhala. East of Middle Street in Honolulu (exit 19A), H-1 is also known as the "Lunalilo Freeway" and is sometimes signed as such at older signs in central Honolulu. West of Middle Street, H-1 is also known as the "Queen Liliuokalani Freeway"; this name is shown on some roadmaps. It is both the southernmost and westernmost signed Interstate Highway in the United States.
Document 5: Overthrow of the Hawaiian Kingdom: The overthrow of the Kingdom of Hawaii began on January 17, 1893, with a coup d'état against Queen Liliuokalani on the island of Oahu by foreign residents residing in Honolulu, mostly United States citizens, and subjects of the Kingdom of Hawaii. They prevailed upon American minister John L. Stevens to call in the U.S. Marines to protect American interests, an action that effectively buttressed the rebellion. The revolutionaries established the Republic of Hawaii, but their ultimate goal was the annexation of the islands to the United States, which finally occurred in 1898.
Document 6: Honolulu: In 1845, Kamehameha III moved the permanent capital of the Hawaiian Kingdom from Lahaina on Maui to Honolulu. He and the kings that followed him transformed Honolulu into a modern capital, erecting buildings such as St. Andrew's Cathedral, ʻIolani Palace, and Ali ʻiōlani Hale. At the same time, Honolulu became the center of commerce in the islands, with descendants of American missionaries establishing major businesses in downtown Honolulu.
Document 7: Cuba–United States relations: The hold of the Spanish Empire on possessions in the Americas was reduced in the 1820s as a result of the Spanish American wars of independence; only Cuba and Puerto Rico remained under Spanish rule until the Spanish -- American War (1898) that resulted from the Cuban War of Independence. Under the Treaty of Paris, Cuba became a U.S. protectorate; the U.S. gained a position of economic and political dominance over the island, which persisted after it became formally independent in 1902.
Document 8: List of states and territories of the United States: The United States of America is a federal republic consisting of 50 states, a federal district (Washington, D.C., the capital city of the United States), five major territories, and various minor islands. The 48 contiguous states and Washington, D.C., are in central North America between Canada and Mexico; the two other states, Alaska and Hawaii, are in the northwestern part of North America and an archipelago in the mid-Pacific, respectively, while the territories are scattered throughout the Pacific Ocean and the Caribbean Sea.
Document 9: 51st state: Puerto Rico has been under U.S. sovereignty for over a century when it was ceded to the U.S. by Spain following the end of the Spanish–American War, and Puerto Ricans have been U.S. citizens since 1917. The island's ultimate status has not been determined as of 2012[update], its residents do not have voting representation in their federal government. Puerto Rico has limited representation in the U.S. Congress in the form of a Resident Commissioner, a delegate with limited no voting rights. Like the states, Puerto Rico has self-rule, a republican form of government organized pursuant to a constitution adopted by its people, and a bill of rights.
Document 10: Area code 808: The 808 telephone area code covers the inhabited, developed and uninhabited areas of the Hawaiian Islands out to Midway Island and Wake Island. 808 was issued as Hawaii's area code in 1957, not long before its statehood in August of 1959.
Document 11: History of Hawaii: The native population succumbed to disease brought by the Europeans (particularly smallpox), declining from 300,000 in the 1770s over 60,000 in the 1850s to 24,000 in 1920. Americans within the kingdom government rewrote the constitution, severely curtailing the power of King ``David ''Kalākaua, and disenfranchising the rights of most Native Hawaiians and Asian citizens to vote, through excessively high property and income requirements. This gave a sizeable advantage to plantation owners. Queen Liliuokalani attempted to restore royal powers in 1893, but was placed under house arrest by businessmen with help from the US military. Against the Queen's wishes, the Republic of Hawaii was formed for a short time. This government agreed on behalf of Hawaii to join the US in 1898 as the Territory of Hawaii. In 1959, the islands became the state of Hawaii of the United States.
Document 12: Hawaiian Islands: The Hawaiian Islands (Hawaiian: Mokupuni o Hawai'i) are an archipelago of eight major islands, several atolls, numerous smaller islets, and seamounts in the North Pacific Ocean, extending some 1,500 miles (2,400 kilometers) from the island of Hawai ʻi in the south to northernmost Kure Atoll. Formerly the group was known to Europeans and Americans as the ``Sandwich Islands '', a name chosen by James Cook in honor of the then First Lord of the Admiralty John Montagu, 4th Earl of Sandwich. The contemporary name is derived from the name of the largest island, Hawaii Island.
Document 13: Hawaii: The Kingdom of Hawai ʻi was sovereign from 1810 until 1893 when the monarchy was overthrown by resident American and European capitalists and landholders. Hawaii was an independent republic from 1894 until August 12, 1898, when it officially became a territory of the United States. Hawaii was admitted as a U.S. state on August 21, 1959.
Document 14: Hawaii (island): Hawaiʻi The Big Island Landsat mosaic, 1999 -- 2001 Location in the state of Hawaii Geography Location 19 ° 34 ′ N 155 ° 30 ′ W ﻿ / ﻿ 19.567 ° N 155.500 ° W ﻿ / 19.567; - 155.500 Archipelago Hawaiian Islands Area 4,028 sq mi (10,430 km) Area rank 75th, largest island in the United States - 1st Highest elevation 13,803 ft (4,207.2 m) Highest point Mauna Kea Administration United States State Hawaii Symbols Flower Red Pua Lehua (ʻOhiʻa blossom) Color ʻUlaʻula (red) Largest settlement Hilo Demographics Population 185,079 (2010) Pop. density 46 / sq mi (17.8 / km)
Document 15: 51st state: Cuba, like many Spanish territories, wanted to break free from Spain. A pro-independence movement in Cuba was supported by the U.S., and Cuban guerrilla leaders wanted annexation to the United States, but Cuban revolutionary leader José Martí called for Cuban nationhood. When the U.S. battleship Maine sank in Havana Harbor, the U.S. blamed Spain and the Spanish–American War broke out in 1898. After the U.S. won, Spain relinquished claim of sovereignty over territories, including Cuba. The U.S. administered Cuba as a protectorate until 1902. Several decades later in 1959, the corrupt Cuban government of U.S.-backed Fulgencio Batista was overthrown by Fidel Castro. Castro installed a Marxist–Leninist government allied with the Soviet Union, which has been in power ever since.
ground_truth: August 12, 1898
sub_queries: which of these was the 50th state to join the united states Answer: Hawaii
when did Hawaii become a part of the united states Answer: August 12, 1898