Why has the Japanese-American population decreased?

[retromike22]

I was reading this: http://en.wikipedia.org/wiki/Demographics_of_Asian_Americans#Asian_American_alone

Group Population, 2000 Population, 2010 Percent change

Chinese    2,564,190    3,535,382    37.9%
Indian    1,718,778    2,918,807    69.8%
Filipino    1,908,125    2,649,973    38.9%
Vietnamese    1,169,672    1,632,717    39.6%
Korean    1,099,422    1,463,474    33.1%
Japanese    852,237    841,824    −1.2%
Pakistani    164,628    382,994    132.6%
Cambodian    183,769    255,497    39.0%
Hmong    174,712    252,323    44.4%
Other Asian, not specified    162,913    238,332    46.3%
Laotian    179,103    209,646    17.1%

How come this happened?

[dpmapper]

An older, highly secular population leading to low fertility (same reason Japan is losing population), plus a negligible amount of immigration (esp. compared with the other ethnicities you listed).  Seems pretty straightforward to me. 

[PiMp DaDdy FitzGerald]

Where is the Korean growth coming from? I mean, there can't be much immigration due to the low birth rate over there.

[H. Ross Peron]

In addition to what dpmapper said, wouldn't another reason be intermarriage becoming fairly common between whites and Japanese-Americans?

[Snowstalker Mk. II]

Where is the Korean growth coming from? I mean, there can't be much immigration due to the low birth rate over there.

Adopted children from Korea plus immigration.

[dpmapper]

There is plenty of Korean immigration, both student and otherwise.  Just check out any H-Mart. 

In addition, since the wave of Korean immigrants is much more recent than the Japanese, it's a younger population overall. 

[jimrtex]

I was reading this: http://en.wikipedia.org/wiki/Demographics_of_Asian_Americans#Asian_American_alone

Group Population, 2000 Population, 2010 Percent change

Chinese    2,564,190    3,535,382    37.9%
Indian    1,718,778    2,918,807    69.8%
Filipino    1,908,125    2,649,973    38.9%
Vietnamese    1,169,672    1,632,717    39.6%
Korean    1,099,422    1,463,474    33.1%
Japanese    852,237    841,824    −1.2%
Pakistani    164,628    382,994    132.6%
Cambodian    183,769    255,497    39.0%
Hmong    174,712    252,323    44.4%
Other Asian, not specified    162,913    238,332    46.3%
Laotian    179,103    209,646    17.1%

How come this happened?

The Census Bureau permits people to report up to 6 races: White, Black, Asian, American Indian or Alaska Native; Native Hawaiian or Pacific Islander; and Other.   For Asian, AIAN, and NHOPI, they then ask for further delineation (eg Japanese, Navajo, or Samoan).

The table you referred to is for persons who reported Asian only.  So someone who reported they were Asian: Japanese and White would not be counted in that table.  The table to its right includes multi-racial person (it is a bit misleading since it also includes Asian-only person).

If you take the difference between the two, the mixed-race Japanese population increased from 296K to 463K.  There has not been large scale immigration from Japan after WWII, the population is not particularly concentrated, and it has not been advantageous to emphasize your Japanese heritage, but rather concentrate on being well educated and being financially successful.  So you end up with mixed-race marriages.   And some of the migration since WWII has been Japanese women marrying American military, which would make the offspring mixed race.

Some people misidentify as Native Hawaiian.  To the extent this is done by Japanese (about 1/4 live in Hawaii), it may undercount persons who are Japanese only (the Japanese population is large enough in Hawaii to permit marriage within the community).

The census also does not count only US citizens, or even permanent residents.  Rather it counts usually resident, which would only exclude a few diplomats.  Someone working for Toyota or Nissan or Honda at an American auto plant, will be reported in the census, and the same would be true for Japanese students attending college.   These groups may have declined with the static Japanese population, and mediocre economy, and some will have assimilated and added one or two children to the mixed-race population.

[ag]

If you do not get into a good primary school in South Korea, your life is, basically, over. Well, primary school is a slight exaggeration - but it is true at the university level. So, if you slipped and fell, you might as well emigrate.

There is, actually, very noticeable Korean immigration in Mexico City, of all places. Surely even more people go to the US.