Neb. Rev. Stat. §§ 77-1901
Counties shall have a lien upon real estate within their boundaries for all taxes due thereon to the state, any governmental subdivision of the state, any municipal corporation, and any drainage or irrigation district. After any parcel of real estate has been offered for sale and not sold for want of bidders, the county board shall make and enter an order directing the county attorney to foreclose the lien for all taxes then delinquent, excluding any lien on real estate for special assessments levied by any sanitary and improvement district which special assessments have not been previously offered for sale by the county treasurer, in the same manner and with like effect as in the foreclosure of real estate mortgages, except as otherwise specifically provided by sections 77-1903 to 77-1917.
Neb. Rev. Stat. §§ 77-1901