Tallgrass Development, LP (“Tallgrass”) and AGL Resources Inc. (“AGL Resources”) announced today that they have successfully concluded the non-binding open season for their proposed Prairie State Pipeline. The pipeline is designed to move natural gas from supply connections in central Illinois to the Chicago Market Center and points in between. Prairie State Pipeline is being jointly developed by Tallgrass and AGL Resources, and is expected to have ownership participation by both companies should binding commitments be finalized with interested market participants.

“The value proposition provided by Prairie State was well received by the broader market, including expressions of interest from both the market and the production communities. The open season results affirmed Tallgrass and AGL Resources’ view that the end-user market needs incremental, reliable infrastructure and would support additional supply diversity,” said Bill Moler, Chief Operating Officer for Tallgrass Development.

Prairie State Pipeline is expected to have a total capacity of 1.2 Bcf/d to 1.5 Bcf/d. The project has received solid expressions of interest and AGL Resources and Tallgrass are working to finalize shipper commitments via precedent agreement. Prairie State Pipeline will provide additional supply diversity and access to the Illinois and Midwest markets, while increasing reliability through new infrastructure construction.

“The Prairie State Pipeline is an important project for the Illinois market. At this stage, we are pleased with the open season results and plan to continue to work with interested shippers and Tallgrass to move this project forward,” said John W. Somerhalder II, CEO of AGL Resources, Inc.

Prairie State Pipeline is expected to consist of nearly 140 miles of large diameter pipeline running in a generally north-south orientation, to connect interstate pipelines in Douglas County, Ill., to gas distribution systems, natural gas storage fields and interstate pipeline companies in the Chicago Market Center. Prairie State Pipeline expects to provide unique access to more than 4.0 Bcf/d of delivery points. Potential delivery points include city-gate and storage interconnects with Nicor Gas, The Peoples Gas Light and Coke Co., Ameren, North Shore Gas Company and possible interstate pipeline interconnects with ANR Pipeline, Guardian Pipeline, Northern Border Pipeline, Horizon Pipeline, Alliance Pipeline and Natural Gas Pipeline Company of America. FERC approval of the Project will be sought once the appropriate design capacity of the Prairie State Pipeline is determined.

About Tallgrass Development:

Tallgrass Development, LP, a private limited partnership organized in Delaware, owns a 50 percent interest in and operates the Rockies Express Pipeline, an approximately 1,712 mile natural gas pipeline which enables producers in the Rocky Mountain and Appalachian Basin production regions to deliver gas to the Midwest and eastern parts of the country. Tallgrass Development owns Tallgrass Terminals which is constructing crude oil terminal facilities near Sterling, Colorado and owns an interest in the Deeprock Cushing crude oil terminal. Tallgrass Development also provides crude oil transportation to customers in Wyoming and the surrounding region, including servicing the Bakken production area of North Dakota and eastern Montana, through its majority ownership interest in Tallgrass Pony Express Pipeline, LLC.

Tallgrass Development is the sponsor of, and owns a significant number of limited partnership interests in, Tallgrass Energy Partners, LP (NYSE: TEP). To learn more, please visit our website at www.tallgrassenergy.com.

About AGL Resources:

AGL Resources Inc. (NYSE: GAS) is an Atlanta-based energy services holding company with operations in natural gas distribution, retail operations, wholesale services and midstream operations. AGL Resources serves approximately 4.5 million utility customers through its regulated distribution subsidiaries in seven states, including approximately 2.2 million customers in Illinois. The company also serves approximately 630,000 retail energy customers and approximately 1.2 million customer service contracts through its SouthStar Energy Services joint venture and Pivotal Home Solutions, which market natural gas and related home services. Other non-utility businesses include asset management for natural gas wholesale customers through Sequent Energy Management and ownership and operation of natural gas storage facilities. AGL Resources is a member of the S&P 500 Index. For more information, visit www.aglresources.com.

Forward-Looking Statements

This press release includes “forward-looking statements.” All statements, other than statements of historical facts, included in this press release that address activities, events or developments that are expected, believed or anticipated will or may occur in the future are forward-looking statements. Without limiting the generality of the foregoing, forward-looking statements contained in this press release specifically include the potential design capacity of the pipeline; the route and length of the pipeline; the potential receipt points, delivery points and delivery interconnects of the pipeline; and the projected in-service date of the pipeline. Such statements are subject to a number of assumptions, risks and uncertainties, many of which are beyond the control of the Tallgrass or AGL Resources, which may cause actual results to differ materially from those implied or expressed by the forward-looking statements. Any forward-looking statement applies only as of the date on which such statement is made. Tallgrass and AGL Resources disclaim any obligation to revise or update any forward-looking statement, whether as a result of new information, future events or otherwise, except as required by law.