“Across the Midwest, we've seen positive growth in the past three or four quarters,” he says. Cincinnati, Cleveland, Columbus, Indianapolis and even Detroit, for example, have all taken part in the recovery.

Although Detroit usually appears at the bottom of any list of US metro areas that measures economic vitality, Sikaitis says such lists don't truly capture what is happening there. “Detroit has seen hefty growth, at least from a regional perspective,” especially the downtown, which he calls “an immature market that has a lot of opportunity for growth.” Health care, tech and creative companies, among others, have set up shop in the CBD seeking to attract all the millennials that want to live and play downtown. Similar transformations have occurred across the US, but “there is no better example of that turnaround than the urban area of Detroit.”

“We're also seeing cities with highly diverse economies such as Chicago and Los Angeles kick in,” Sikaitis says. “Their economies are starting to move at a faster clip than the rest of the nation.”

A set of big second quarter leases from a diverse collection of companies demonstrated the depth of Chicago's office market. AbbVie, a pharmaceutical research and development company, subleased 490,000-square-feet at 26525 N. Riverwoods Blvd. in the northern suburbs, according to JLL. William Blair, an investment banking firm, signed a prelease for 318,000-square-feet in the proposed development at 150 N. Riverside Dr. in the CBD. And in perhaps the best sign of the market's future direction, Google expanded by 105,000-square-feet at 1000 W. Fulton in the city's old meatpacking district, bringing its footprint in this new high-tech center to 357,000-square-feet.

Tenants leased about 8.9-million-square-feet of space in New York this quarter, much of it for large leases, JLL found. And tech firms continue to drive the San Francisco market, which saw 2.7-million-square-feet of leasing. In “the largest lease in the city's history,” Salesforce recently preleased 714,000-square-feet at 415 Mission St., “which will be the tallest building on the West Coast upon its completion in 2017.”

Among the major markets, Washington, DC remains a bit of an outlier. Its office market continues to suffer from the slump in demand from government and government contractors. However, Sikaitis says “we've seen a little bit more stability in the last four to five months than we have in the last couple of years.”

And there are signs that the acceleration of leasing will continue across most of the country. For example, many brokers surveyed by JLL report that they have taken an increasing number of companies considering future moves on tours of office space. Nearly half of those surveyed reported an increase, and “there is no market showing a down tick in touring velocity,” Sikaitis says.

But accelerated leasing is not the only sign of the office market's recovery.

“We've seen a significant uptick in construction activity since the end of 2013.” Developers have about 65-million-square-feet under construction, a 38.4% increase from the end of 2013. However, unlike the pickup in leasing, the expansion in office construction is more geographically limited. For example, developers have about 15-million-square-feet under construction in Houston alone, or about 23% of the national total. And the top ten markets account for roughly 69% of all development activity.

“Consistent rent growth is likely to persist through 2016, when the majority of markets will reach the peaking phase of their cycle,” the new JLL study concludes. “However, leading markets such as Houston, San Francisco, Silicon Valley and Dallas will peak earlier due to significant construction underway, while a few lagging markets will reach that point in 2017 or later.”