acre. A unit for measuring land. A square mile includes 640 acres.

altitude. How high something is above the Earth or above sea level.

amendment. An addition or change made to a law or constitution.

Anasazi. A name the Navajo gave to the Ancestral Puebloan people of the Four Corners area. The word means “ancient enemies” or “ancient people who are not us.”

ancestor. A person from whom one is descended, or an earlier relative, such as a grandparent or great-grandparent.

aquifer. An underground layer of rock that contains water.

archaeologist. A person with special training who collects evidence about how people lived in past ages.

artifact. An object produced by a human being, such as a tool, a weapon, or jewelry.

band (Indian). A small group or village of Indians who lived and hunted together. Tribes were made up of many bands.

blacksmith. A person who shapes iron to make horseshoes and other useful items. The individual beats the hot iron on an anvil with a hammer.

brand. An owner’s mark burned into the hide of an animal with a hot iron.

canyon. A washed-out area with steep cliff walls. Canyons are formed by fast-running water.

capital cities. Cities where at least the legislative branch of a government is located.

capital resources. Tools and other items used to make goods and services to sell.

causes. People or events that make things happen that are either distant in time (remote causes) or recent in time (immediate causes).

change. To go from one condition or way of living to another.

checks and balances. Ways to keep a balance of power among different branches of government.

citizens. Individuals who owe loyalty to a nation in which they were born or naturalized as citizens.

citizenship. Carrying out the duties and claiming the rights of being a citizen.

Civil Rights Movement. People and organizations who came together to provide minority groups with their basic rights as citizens.

climate. The temperature, moisture, and wind typical of a region or particular area.

coal mining. Digging coal, a black substance composed of fossilized plants used as a fuel, out of the earth.

coniferous. Evergreen trees that produce cones, such as pine and spruce.

consequence. An effect or what happens as a result of an action or event.

conservationists. People who work to protect and preserve natural resources.

constitution. A document or set of laws that creates a government; it describes how the government is organized and what powers it has.

continuity. Things happening as they always have, with little or no change.

corrida de gallo. A sporting event played by riders racing on horseback. They try to reach down and grab the head of a rooster that is buried in the ground up to its neck.

culture. A people’s way of life, including their art, beliefs, and religions.

democracy. A government in which power comes from ordinary citizens.

descendants. Persons who are related to ancestors who lived before them.

drought. A long period with no rain.

Dust Bowl. An area on the plains where the topsoil was blown away by strong winds during the 1930s.

economic incentive. Something that encourages people to make or buy things or to invent new products (positive incentive) or that discourages them from doing so (negative incentive).

effect. A consequence or what happens as a result of an action or event.

elevation. The height at which something rises above the ground or above sea level.

European. Something that came from Europe or people who came from there.

expedition. A journey undertaken by a group of people for a particular purpose.

extended family. A family made up of parents, children, and other close relatives, such as grandparents or aunts and uncles.

extinct. Something that has died out.

farmhand. A person (usually a man) who gets paid to work on a farm.

flour mill. A building in which wheat or other grain is ground into flour.

fossil. An imprint on rock left by bones, leaves, or other objects from past ages.

gatherers. People who lived by finding and collecting plants, seeds, and roots.

general store. A store that sold many kinds of products, such as groceries, meat, tools, and clothing.

Great Depression. The economic slump, or hard times, that took place during the 1930s.

hard-rock mining. Removing gold, silver, or other minerals from quartz rock.

high plains. The central plains of eastern Colorado, which are higher in elevation than the lower river valleys.

historical period. A length of time in the past known for a particular kind of change or way of life.

human resources. The people who produce goods and services.

immigrant. A person who leaves one country to settle in another country.

irrigate. To bring water by ditches or pipes to land that otherwise would be too dry to farm.

landscape. The surface of the land that can be viewed from any one place.

latitude. The distance on the Earth’s surface measured north and south from the Equator.

limited government. A government that has only those powers listed in its constitution or basic laws.

livestock. Animals such as cattle, horses, or pigs raised for home use or to sell.

location. Where a place is situated or can be found on a map.

longitude. The distance on the Earth’s surface measured in degrees from the prime meridian at Greenwich, England.

Los Pastores. A play about the birth of Christ performed on Christmas Eve in Hispanic communities.

merchant. A person who sells goods to customers, such as a shop owner or storekeeper.

mesas. High places or landforms that have a flat top and cliff-like sides.

mine tailings. The waste rock taken from a mine that is left on the mountainside.

mules. Animals that are a hybrid of a horse (mother) and a donkey (father).

national park. An area of land set aside by the national government for public use.

native culture. A people’s way of life before newcomers arrive.

natural resources. Objects found in nature that can be used to produce goods and services, such as land, water, and minerals.

Navajo. An Indian tribe that lives in New Mexico, Arizona, and Utah.

nuclear power. Using atomic energy to generate power, usually by heating water to create steam.

open range. Unfenced grassland owned by the federal government on which cattle grazed.

opportunity cost. Giving up the next-best choice when you choose one thing over another.

ore. A natural substance such as rock that contains gold, silver, or other valuable minerals.

oxen. Male cattle trained to pull wagons and plows.

pathfinder. A person who discovers or finds his or her way into an unexplored region.

patron saint. A holy person whose spirit guards a nation, place, or person.

piedmont. The region that lies between the Front Range of the Rocky Mountains and the high plains of eastern Colorado.

pithouse. A shelter built of poles and dried mud with a floor just below the level of the ground.

place. The space at which something is located, such as a town or city.

placer mining. Using moving water to separate flakes or nuggets of gold from gravel and soil taken from the bed or bank of a stream.

plateau. An elevated, generally flat area of land; a tableland.

plaza. An open area where people gather. In early Spanish American settlements, the plaza was surrounded on all four sides by rooms or walls.

pottery. Pots, bowls, or plates made from moist clay and hardened by heat.

powwow. A meeting or gathering of American Indians.

precious metals. Metals such as gold and silver that have a high value.

precipitation. Moisture that falls in the form of rain or snow.

primary source. A firsthand or eyewitness account by someone who lived at the time.

pueblo. A village or large community dwelling (up to five stories in height) built by Indians of the American Southwest.

Pueblo Indians. Indian people who live in New Mexico and Arizona, related to the Ancestral Puebloans.

raid. A surprise attack against an enemy camp, village, or fort.

rawhide. The untanned hide of animals.

referendum. A vote directly by the people on an issue or whether a measure will become a law.

region. A geographic area in which places or landforms have much in common.

rendezvous. A meeting place and time arranged beforehand.

representative democracies. Governments in which people elect others to represent them in a legislature.

reservation. Land set aside by the United States government as living space for American Indian tribes.

reservoir. A body of water stored in a natural or human-made lake.

resort. A place to which people go to relax and have fun.

roundup. Herding together cattle that range on the open plains so calves can be branded and older cattle shipped to market.

rural. Having to do with the country rather than the city, or related to farming.

scarcity. Not having enough resources to satisfy people’s needs and wants.

sea level. The level of the ocean’s surface, used as the base to measure the elevation of land or the depth of the sea.

secondary source. An account based on primary sources written by someone who lived at a later time.

segregated. Providing separate schools, housing, or services based on race.

semiarid. Having too little snow and rainfall (10–20 inches per year) to grow crops without irrigation.

separation of powers. Dividing power among different branches of government.

significance. Being important, having an impact, or being valuable.

sod house. A house made of grass-covered soil held together by roots.

sorghum. A plant grown for its grain or as animal feed; also a source of syrup.

spatially. How places are located in relation to each other.

statehood. Being a state rather than a territory of the United States.

steel mill. A building where iron ore is heated in blast furnaces to be made into steel.

suburbs. Small towns and communities where people live close to the larger cities where they work.

suffrage. Having the right to vote.

territory. A part of the United States that has not been admitted as a state. A territorial government has a legislature elected by the people but no senators or members of Congress. The governor and other top officials are appointed by the president of the United States.

trading post. A store where traders from the outside come to exchange goods for furs or other local products.

trappers. People who trap wild animals for their skins.

travois. A frame made of poles pulled by a horse. The Plains Indians used it to carry their belongings from one place to another.

treaty. A written agreement between two or more states or between Indian tribes and the United States concerning trade, peace, or ownership of land.

tribal government. The elected officials who make and enforce laws for Indian tribes.

tribes. The large groups to which villages or bands of Indians belong.

tundra. The area of a mountain above tree line. Only low-growing plants and shrubs can survive because of the tundra’s cold climate, frozen subsoil, and harsh winds.

uranium. A silver-white metal that is radioactive. It is used for fuel for nuclear weapons and power plants.

urban corridor. The area in Colorado along the Front Range of the Rocky Mountains where the largest cities and most of the population are located.

vein. A long, narrow deposit of ore that contains gold, silver, or other minerals.

village. A small town or cluster of shelters.

World War I. A war in Europe from 1914 to 1918 in which the United States and its allies fought Germany, Austria, Hungary, and Turkey.

World War II. A war in Europe, Africa, and Asia from 1939 to 1945 in which the United States and its allies fought Germany, Italy, and Japan.