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A drive along the lakefront gives a view of a residential boom. New high-rise condo buildings in Streeterville and the South Loop house thousands of people where almost no one lived a decade ago. Now that it’s chic to be urban, suburban empty-nesters are joining young professionals and students in enjoying the downtown lifestyle.

Do those shimmering glass towers mean that the city now has the upper hand in growth over the suburbs?

Well, no.

No one is sure exactly how many suburbanites are making the back-to-the-city move, but new analyses of government data indicate that the impact of reverse migration on the makeup of the city is, at most, minor.

Nationwide, very few seniors leave their suburban homes for the central city in their home metropolitan region. In 2003, an estimated 1.4 million Americans over the age of 65 moved, but only 51,000, or not quite 4 percent, made this suburb-to-city trek.

Instead, senior citizens were much more likely to leave their metro area behind: About 785,000 did so that year, or 57 percent of all seniors who moved. “Most of those people are going to Phoenix, to Florida, and places like that,” said demographer Kenneth M. Johnson of Loyola University Chicago.

Locally, relatively few people trade their suburban digs for city homes or apartments. Census data show that, in 2000, only about 80,000 Chicagoans of all ages had moved into the city from the suburbs during the previous five years, or about 3 percent of the city’s populace.

Many of those were single men and women in their 20s, just out of college, who settled into hot neighborhoods, such as Wicker Park and Lakeview. Their sojourn in the big city, though, doesn’t usually last more than a decade before, with a spouse and a family, they tend to return to the suburbs.

More recent data, developed by Johnson, tracking population shifts between 2000 and 2005, show that the in-migration of suburbanites and others is nowhere near as large as the out-migration of Chicagoans.

During that period, the city suffered a net migration loss of 329,840. That means that the number of people who moved out of Chicago to the suburbs and elsewhere in the U.S. was nearly a third of a million more than the number of people who moved in from those areas.

It’s common knowledge that Chicago’s population is being buoyed by an infusion of immigrants, mainly from Mexico. That’s certainly true — as far as it goes. Between 2000 and 2005, the city showed a net gain of nearly 138,827 residents because of immigration. Those new residents from other nations somewhat counterbalanced the loss of people who moved to the suburbs and elsewhere in the U.S.

But what really did the most to compensate for that loss wasn’t immigration, but babies — hundreds of thousands of them. Johnson found that, during that five-year period, a quarter of a million babies were born in Chicago (257,932) while only 120,417 city residents died.

It was because of those infants and, to a lesser extent, those immigrants that, between 2000 and 2005, the city’s population dropped by just 53,498.

Who’s having those babies? Mainly Hispanics, many of whom are immigrants themselves or the children of immigrants.

Johnson’s data for a slightly different period — 2000 to 2004 — show that, for every Hispanic death in Chicago, there were 10 children born to Latino parents. That’s because the Mexicans and other Spanish speakers immigrating to the U.S. are mainly young adults. The influx is still new enough that there just aren’t very many elderly Hispanics in the city.

By contrast, there were about three African-American babies born for every black Chicagoan who died. For whites there was roughly one birth for each death.