at Northern vs in northern

Some examples from the web:

• He saw her at Northern Care.
• Monica Archer was a nurse at Northern Omaha Medical, and she worked pro Bono with disabled veterans at the V.A.
• And you'll have another look at Northern Sky Laboratories.
• Renowned Economics Professor at Northern Cal university.
• PCI Germany internal line between Brunsbüttel-Groβgartach and Wilster-Grafenrheinfeld (DE) to increase capacity at Northern and Southern borders
• Why did you not wait at northern gate as ordered?
• Why did you not wait at northern gate as ordered?
• - I saw you at the Northern Open.
• I just got a call from Louie at the Northern.
• Dr. Rathburn just got in an unmarked Lincoln Town Car at the northern edge of the park.
• Have a taste of our culture like a juicy papaya At the northern-most pyramid built by the Maya.
• Monica Archer called a friend at the Northern Omaha children's hospital about an abandoned 13-year-old boy.
• I'll meet you at the Northern in half an hour.
• Now, with Stawell taken, she has a base at our northern border, which can only mean one thing.
• I understand we're both staying at the Great Northern.
• His mother was a poor immigrant chambermaid at the Great Northern.
• Emergency up at the Great Northern.
• I'll start at the northern edge of the trajectory zone and work my way towards you.
• The mouth of the Gulf is closed by a line commencing at the northern tip of Ra's Musandam and running due east to the coast of Iran.
• Look at these rocks in Northern Scotland.

Some examples from the web:

• American bombers have attacked synthetic gasoline plants in northern, central, western and eastern Germany.
• Subject: Toll payment devices on motorways in northern Portugal
• He's still in northern Florida.
• There'd been a nuclear incident at a research facility in northern Mongolia.
• My second question concerns Turkey's position with regard to the Kurds in northern Iraq.
• The Union remains in favour of the maintenance of a Kurdish enclave in northern Iraq.
• There's a story like that in northern Europe.
• He just got back from a tour in northern Afghanistan.
• We're the top luxury broker in northern California.
• The American company Chevron has won a tender to start shale gas exploration in northern Bulgaria.
• On 2 September, Human Rights Watch charged Turkey and Iran with killing civilians in northern Iraq.
• Not long ago, when I visited Paredes, in northern Portugal, residents alerted me to the municipality's sewerage problems.
• Cooperatives supply water to residents in various parts of the municipality of Paredes in northern Portugal.
• The Council remains deeply concerned about the conflict in northern Uganda.
• Moreover, the Community contributed ECU 8 m to rehabilitation projects in northern Iraq in 1994/95.
• But planning permission in northern Germany must not be held up by a legal action brought 1500 km further south.
• Benito Mussolini has been hiding out in northern Italy, but he plans an escape to Spain...
• Over the last decade there has been a sharp rise in cancer cases in northern Kosovo.
• This ancient-walled city in northern Italy became a center for a group of doctors determined to find a way to boost cycling performance.
• The Council remains deeply concerned by the situation in northern Uganda and the attacks and atrocities carried out by the 'Lord's Resistance Army' (LRA) in northern Uganda and southern Sudan.