Missing 77-year-old George Bass was seen at Harrogate bus station at around 12pm on Wednesday, March 2.
North Yorkshire Police are now extending their search for George to Leeds, believing he was boarding a bus bound to the city.
George was last seen boarding the bus on Wednesday, the day he was reported missing, with police now searching the Harrogate and Leeds area as well as the bus network.
Officers have reiterated their appeal to anyone travelling on public transport in the Harrogate and Leeds area to contact them if they have seen George or know of his current whereabouts.
Police have urged George to get in touch with his family or the police if he sees the appeal for his safety.
George is described as white, 5ft 4in tall with grey receding hair, brown eyes and a pale complexion. He was last seen wearing a grey waterproof jacket with a blue fleece underneath, brown trousers, a dark blue hat, dark blue gloves and black shoes.
Anyone with any information is urged to contact North Yorkshire Police on 101, select option 1 and pass information to the Force Control Room. Alternatively, the missing people charity 116 000 in confidence.