I would say mostly economic factors: common currency, common market, wide-scale trade among the countries. If one country is hit, the others will also suffer: this brings in the feeling of solidarity.
other than that, European culture is actually quite unified, with many shared valued, such as universal health care and religious freedom, yet connection to Christianity.
1)their education system is different from other countries
2)their languages differ according to territorial limits (meaning boundaries )
3)there are better social services compared to other countries
FBI: Federal Bureau of Investigation
IRS: Internal Revenue Service
FCC: Federal Communications Commission
NCAA:<---- there are many abbreviations to this, in what context are you looking at?
