1 industry ranking on its World's Most Admired Companies list.
NSR increased by 5% with strong growth in both our Americas and international segments.
Wins totaled $3.6 billion with a 1.4 book-to-burn ratio in our Americas design business, and a 1.2 book-to-burn ratio across our global design business.
The segment adjusted operating margin increased by 60 basis points to 13.7%, reflecting continued investments in organic growth and innovation, the benefits of our highly efficient global delivery capabilities and the high value our teams are delivering for our clients.
Our focus on deploying innovation and digital tools to transform how we deliver for clients against a backdrop of increasing demand for advisory and program management services supports our guidance for this year and our 17% longer-term margin target.
Adjusted EBITDA increased by 10% and adjusted earnings per share increased by 44%.
Including $213 million of stock repurchases in the first quarter, we have now repurchased $1.2 billion of stock since September 2020, when we launched our repurchase program, or 14% of our outstanding shares.
Our federal, state and local clients are gearing up for several years of sustained increases in infrastructure investment, which includes the expected benefits of the $1.2 trillion Bipartisan Infrastructure Law.
However, our state and local clients, which account for nearly 25% of our NSR, are reporting record revenues and budget surpluses, which is resulting in a very favorable backdrop.
For example, our leadership team identified 10 global pursuits that we deem to be a top priority for strategic positioning and for delivering on our accelerating growth expectations.
I'm very pleased to report that we've already won eight of these 10 projects, and two are still pending decisions.
Tax was a $0.04 benefit to earnings per share compared to our plan due to the timing and quantum of discrete items.
We also delivered on our capital allocation commitments, including ongoing investments in our teams and digital AECOM, more than $200 million of share repurchases and the initiation of a quarterly dividend program.
In the Americas, NSR increased by 3%, highlighted by growth in both the design and construction management businesses.
Our book-to-burn in the Americas design business was 1.4, and total backlog in design business increased by 5%, which continues to include a near-record level of contracted backlog, which provides for strong revenue visibility.
First quarter adjusted operating margin was 17.7%, a 30-basis-point increase from the prior year.
NSR increased by 7%, with growth across all of our largest regions.
Our wins were strong and backlog increased by 6%.
Our adjusted operating margin in the first quarter was 8.2%, a 110-basis-point improvement from the prior year.
First quarter operating cash flow was $195 million and free cash flow was $163 million.
As we look ahead, we continue to expect to convert our earnings to cash flow at a high rate, and we continue to expect free cash flow of between $450 million and $650 million in fiscal 2022.
We are increasing our fiscal 2022 adjusted earnings per share guidance to between $3.30 and $3.50, which would reflect 21% growth at the midpoint.
We also continue to expect to deliver adjusted EBITDA of between $880 million and $920 million, which would reflect 8% growth at the midpoint of the range.
Based on our strong start to the year, we are also reaffirming our expectation for organic NSR growth of 6%, a segment adjusted operating margin of 14.1% and our long-term 2024 financial targets, including adjusted earnings per share of greater than $4.75 and approximately $700 million in free cash flow.
We expect our full year tax rate to be 25%, which incorporates the impact of our first quarter tax rate and the expectations for approximately 28% for the rest of the year.

Summary:
1 industry ranking on its World's Most Admired Companies list.
We are increasing our fiscal 2022 adjusted earnings per share guidance to between $3.30 and $3.50, which would reflect 21% growth at the midpoint.