A.2.1. Alaska, Hawaii, D.C., and Other Areas

From 1913 to 1959, Alaska and Hawaii do not record reliable data due to (1) the excessive amount of missing values for early years of the time period, (2) to the lack of Census data in terms of household units prior to 1960 (when Hawaii was not a U.S. state yet, a U.S. territory only).

Alaska

1921-1938 and 1943-1954: Alaska is included in Washington state. To separate Alaska from Washington state, we calculated r, the growth rate of the share of Alaska in the total of the two states between 1942 and 1955, assuming a linear progression of this share annually:

(A.1) r = (Alaska share ₁₉₅₅ / Alaska share ₁₉₄₂)1/13 - 1

Using this constant rate, it is straightforward to derive the annual values of Alaska’s share:

(A.2) Alaska share_n = Alaska share₁₉₄₂ * (1 + r)n, with n = 1943 to 1954

Defined as Alaska / (Alaska + Washington), the Alaska share contains only one unknown at this point: the numerator. After Alaska data are deduced, Washington is just the difference between the two states taken together and Alaska just estimated. Likewise for time period 1921-1938.

Hawaii

The island became a United States territory in 1900, and was admitted as the 50th state in 1959.

1913-1959: Alaska and Hawaii do not record reliable data due to (1) the excessive amount of missing values for early years of the time period, (2) to the lack of Census data in terms of household units prior to 1960 (when Hawaii was not a U.S. state yet, a U.S. territory only). It is therefore possible to encounter unexplained results like the one for Alaska in 1957, with a drop in TI99.5 below its minimum level.

District of Columbia

1961 and 1962: District of Columbia is included in Maryland for these two years. The 1960 and 1963 data are used to proxy the two variables (number of returns and adjusted gross income) for 1961 and 1962. However, the income class [$10,000-$15,000) in 1960 does not provide information for the intermediate income classes [$10,000-$11,000), [$11,000-$12,000), [$12,000-$13,000), [$13,000-$14,000), and [$14,000-$15,000) as 1963 does. The missing classes for 1960 where estimated by applying to 1960 the same percentage that each intermediate income class represents in the [$10,000-$15,000) total of 1963.

(A.3) V ₁₉₆₃ = V ₁₉₆₀ (1 + r)3 , where r = (V ₁₉₆₃ / V ₁₉₆₀)1/3 – 1.

Puerto Rico and the Virgin Islands

The United States took possession of Puerto Rico and the Virgin Islands in 1898, and 1917, respectively. Unlike the Virgin Islands, Puerto Rico became a Commonwealth on July 25, 1952 (Source: National Park Service, U.S. Department of the Interior).

1913-1951: Puerto Rico is included in Maryland.

1917-1951: Puerto Rico and Virgin Islands are included in Maryland.

1952: Puerto Rico is included in both Maryland (1st half of 1952) and New York (2nd half of 1952). Nothing is mentioned about the Virgin Islands.

1953: Puerto Rico and Virgin Islands are included in New York.

1954: For the first time, Puerto Rico is a separate entity in the State and Territory classification.

1954 on: Puerto Rico and Virgin Islands are grouped together and they either appeared separately or were added to the ‘Other Areas’ category.

Panama Canal Zone

The United States Protectorate in the Republic of Panama started with the Treaty of 1903.

1913-1954: Panama Canal Zone is included in Florida.