Aldie is an unincorporated community located between Chantilly and Middleburg in Loudoun County, Virginia. Aldie's historic heart is the Village of Aldie that is located on the John Mosby Highway in a gap between the Catoctin Mountains and Bull Run Mountains, through which the Little River flows. Aldie traditionally serves as the gateway to Loudoun Valley and beyond.As of 2014, the Aldie postal area had a population of 11,420 people, a 569% increase since 2000 making it one of the fastest growing suburbs in the Washington, D.C. metropolitan area and the second fastest growing zip code in Virginia. As a result, the eastern part is suburbanized with numerous upscale communities recently built or under construction while most of the Aldie Hills adjacent to the historic Village of Aldie have so far largely preserved their bucolic character.