Taxes on unimproved land are low.    From Wordnet, Princeton University. 

A farm with 50 acres of unimproved and 68 acres of improved land.    From Wordnet, Princeton University. 

Adjective : an unimproved opportunity. ,Our chance of success is unimproved.    From Dictionary.com. 

The road to Potato Cove was the kind that map makers call "unimproved," meaning that it was gravel with teeth-rattling bumps and ruts.    From Wordnik.com.  [The Cat Who Moved A Mountain]

Under the program, new or converted homes and condominiums are taxed only on the previous, "unimproved" value of the property for 10 years.    From Wordnik.com.  [The Taxes of Philadelphia] Reference

Highways: total: 510 km paved: 30 km unpaved: gravel 80 km; unimproved earth 400 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 1,137 km paved: 455 km unpaved: improved, unimproved earth 682 km (1988).    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

The trouble with unimproved earth roads is that they are muddy for many months in the year.    From Wordnik.com.  [Hidden Treasure] Reference

Highways: total: 2,900 km paved: 280 km unpaved: improved, unimproved earth 2,620 km (1982).    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

The houses were few, low, not handsome, with hideous spaces of unimproved land lying between.    From Wordnik.com.  [The Life of Abraham Lincoln] Reference

Highways: total: 26,429 km paved: 2,868 km unpaved: gravel 11,421 km; unimproved earth 12,140 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 300 km paved: 125 km unpaved: otherwise improved 125 km; unimproved earth 50 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 1,000 km paved: 600 km unpaved: otherwise improved 300 km; unimproved earth 100 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

We have seen that the farm lands of Virginia, improved and unimproved, constituted 31,014,950 acres.    From Wordnik.com.  [The Continental Monthly, Vol. 3, No. 1 January 1863 Devoted To Literature And National Policy] Reference

Highways: total: 4,000 km paved: 950 km unpaved: otherwise improved 900 km; unimproved earth 2,150 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

The outlook for the Social Security trust fund, however, was unimproved from last year's projections.    From Wordnik.com.  [Report Finds Health-Care Law Benefits Medicare] Reference

Highways: total: 10,000 km paved: 1,500 km unpaved: gravel 4,100 km; improved, unimproved earth 4,400 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 3,083 km paved: 431 km unpaved: gravel, crushed stone 501 km; unimproved earth 2,151 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 69,942 km paved: 7,459 km unpaved: improved earth 13,538 km; unimproved earth 48,945 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 8,950 km paved: 1,700 km unpaved: otherwise improved 5,000 km; unimproved earth 2,250 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 59,474 km paved: 29,440 km unpaved: gravel, crushed stone, improved earth, unimproved earth.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 4,885 km paved: 880 km unpaved: gravel, sand and gravel 1,305 km; unimproved earth 2,700 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 8,530 km paved: 2,745 km unpaved: gravel, crushed stone 3,270 km; improved, unimproved earth.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 12,000 km paved: 5,800 km unpaved: gravel or improved earth 5,600 km; unimproved earth 600 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 24,127 km paved: 3,289 km unpaved: gravel 6,664 km; improved earth 1,652 km; unimproved earth.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

They saw their last opportunity for a successful rebellion, and they determined not to let it pass unimproved.    From Wordnik.com.  [The Continental Monthly , Vol. 2 No. 5, November 1862 Devoted to Literature and National Policy] Reference

Highways: total: 15,700 km paved: 1,670 km unpaved: gravel, improved earth 3,670 km; unimproved earth 10,360 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 3,845 km paved: 807 km unpaved: gravel 840 km; improved earth 402 km; unimproved earth 1,796 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 26,498 km paved: 4,593 km unpaved: gravel, crushed stone, stabilized earth 829 km; unimproved earth 21,076 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Highways: total: 3,300 km paved: 1,590 km unpaved: gravel, crushed stone, stabilized earth 1,290 km; unimproved earth 420 km (1984).    From Wordnik.com.  [The 1995 CIA World Factbook] Reference

Increased land taxes force unimproved land upon the market, and compel its improvement, to escape loss in holding it unimproved and idle.    From Wordnik.com.  [Socialism As It Is A Survey of The World-Wide Revolutionary Movement] Reference

Highways: total: 140,200 km paved: 42,694 km unpaved: gravel, crushed stone 46,866 km; improved earth 49,440 km; unimproved earth 1,200 km.    From Wordnik.com.  [The 1995 CIA World Factbook] Reference