Segregation in Northern Ireland is a long-running issue in the political and social history of Northern Ireland. The segregation involves Northern Ireland's two main voting blocs—Irish nationalist/republicans (mainly Roman Catholic) and British unionist/loyalist (mainly Protestant). It is often seen as both a cause and effect of the "Troubles". A combination of political, religious and social differences plus the threat of intercommunal tensions and violence has led to widespread self-segregation of the two communities. Catholics and Protestants lead largely separate lives in a situation that some have dubbed "self-imposed apartheid". Education Education in Northern Ireland is heavily segregated. Most state schools in Northern Ireland are predominantly Protestant, while the majority of Catholic children attend schools maintained by the Catholic Church. In 2006, 90 per cent of children in Northern Ireland were in segregated schools, by 2017 that figure had risen to 93%. The consequence is, as one commentator has put it, that "the overwhelming majority of Ulster's children can go from four to 18 without having a serious conversation with a member of a rival creed." The prevalence of segregated education has been cited as a major factor in maintaining endogamy (marriage within one's own group). The integrated education movement has sought to reverse this trend by establishing non-denominational schools such as the Portadown Integrated Primary. Such schools are, however, still the exception to the general trend of segregated education. Integrated schools in Northern Ireland have been established through the voluntary efforts of parents. The churches have not been involved in the development of integrated education. However, both the Catholic Church and Protestant denominations, along with state-run institutions, have supported and organised cross-community school projects such as joint field trips, educational classes and forums wherein pupils can come together to share their beliefs, values and cultures. The academic John H. Whyte argued that "the two factors which do most to divide Protestants as a whole from Catholics as a whole are endogamy and separate education". Employment Historically, employment in the Northern Irish economy was highly segregated in favour of Protestants, particularly at senior levels of the public sector, in certain then-important sectors of the economy, such as shipbuilding and heavy engineering, and strategically important areas such as the police. Emigration to seek employment was therefore significantly more prevalent among the Catholic population. As a result, Northern Ireland's demography shifted further in favour of Protestants leaving their ascendancy seemingly impregnable by the