Populate DropDownlist with Places without using Database in ASP.Net

Hello Professionals,

I have a USA Cities and towns list in SQL Script formate with 5000+ entries, i have asked to implement it that when user type in textboxt of "Select City" a whole list should be popup in the dropdown matching with the entered keywords, i'm restricted not to use database. Can anybody help me out how can i proceed with  it? i don't want to show whole entries on the page load as it will take much time while loading big data, Please suggest me a solution . Thank you.