although a high proportion of the population is known to have multiple ancestries, in the 2000 census, the first with the option to choose more than one, most people still identified with one racial category. in the 2000 census, self-identified german americans made up 17.1% of the u.s. population, followed by irish americans at 12%, as reported in the 2000 u.s. census. this makes german and irish the largest and second-largest self-reported ancestry groups in the united states. both groups had high rates of immigration to the u.s. beginning in the mid-19th century, triggered by the great famine in ireland and the failed 1848 revolution in germany. however, english americans and british americans are still considered the largest ethnic group due to a serious under count following the 2000 census whereby many english and british americans self-identified under the new category entry 'american' considering themselves 'indigenous' because their families had resided in the us for so long or, if of mixed european ancestry, identified with a more recent and differentiated ethnic group.