While most people are familiar with the concept of gentrification, not everyone knows about a new phenomenon dubbed youthification.

Instead of a neighborhood's population changing in terms of economic or social status due to new residents, the trend of youthification describes an influx of young adults, aged 25 to 34, and the effects that change has on an area.

Dr. Markus Moos, a geographer and urban planner at the University of Waterloo, coined this process youthification "to explain the phenomenon of young adults moving centrally (within a metropolitan area) as a result of rising affordability concerns, growing demand for urban lifestyles, a desire to get around without a car, declining household size and growing educational attainment, among other factors," as he wrote on the website for his 'Generationed City' project.

Moos explains that youthification occurs through a number of stages. It starts with younger people moving into relatively inexpensive neighborhoods, perhaps those with spaces leftover from de-industrialized manufacturing districts. As the process continues, newer rental housing and one-bedroom apartments are built and amenities like restaurants and bars are added, helping draw greater numbers of young people even as the cost of living rises.

As part of his project, Moos charts the most 'youthified' metropolitan cities in the United States and Canada according to the percent of the population that falls between ages 25 and 34.

Salt Lake City ranks No. 1 on the list with 16.93 percent of its population falling within that age range, and — perhaps unsurprisingly — the Austin-Round Rock-San Marcos area came in at No. 2.

The Houston-Sugar Land-Baytown area was ranked No. 9 in the U.S. and Canada with 15.13 percent of the population falling between 25 and 34. In Houston, most of the areas with the highest concentration of young adults are located within six miles of the city's center (essentially within the 610 Loop).

Moos notes that the more pronounced generational divide seen in some metropolitan cities — such as in Houston — is likely a result of socioeconomic shifts.

As young people in the U.S. and Canada experience reduced job security, less assistance from the social safety net, growing housing prices, delayed childbearing and an increased desire for urban living, they are opting to live closer to city centers where apartments are more readily available. Moos adds that it's unclear as to whether this pattern will continue or if those moving to city centers in their twenties and thirties will eventually move out to the suburbs to raise their children.

Although pronounced, the generational segregation observed in metropolitan cities is not as obvious as an ethnic or class divide, Moos finds, although he adds that "there are clear signs of a process of youthificiation underway that is indeed creating generationed spaces in our cities that, if intensified in the future, could lead to further inter-generational conflict."