Rhoticity is common in most American accents although it is now rare in England because during the 17th-century British colonization, nearly all dialects of English were rhotic, and most North American English simply remained that way. The preservation of rhoticity in North America was also supported by continuing waves of rhotic-accented Scotch-Irish immigrants, most intensely during the 18th century and moderately during the following two centuries, when the Scotch-Irish eventually made up one seventh of the colonial population. Scotch-Irish settlers spread from Delaware and Pennsylvania throughout the larger Mid-Atlantic region, the inland regions of both the South and North and throughout the West, American dialect areas that a consistently resisted upper-class non-rhotic influences and that consequently remain rhotic today. The pronunciation of is a postalveolar approximant or retroflex approximant , but a unique "bunched tongue" variant of the approximant "r" sound is also associated with the United States and perhaps mostly in the Midwest and the South.