Invasive species in the United States

Invasive species are a signifcant threat to many native habitats and species of the United States and a significant cost to agriculture, forestry, and recreation. The term "invasive species" can refer to introduced or naturalized species, feral species, or introduced diseases. There are many species that are invasive. Some species, such as the dandelion, while non-native, do not cause significant economic or ecologic damage and are not widely considered as invasive. Overall, it is estimated that 50,000 non-native species have been introduced to the United States, including livestock, crops, pets, and other non-invasive species. Economic damages associated with invasive species' effects and control costs are estimated at $120 billion per year.

For a more complete list of invasive species, see List of invasive species in North America

The economic impacts of invasive species can be difficult to estimate, especially when an invasive species does not affect economically important native species. This is due in part to the difficulty in determining the non-use value of native habitats damaged by invasive species, and in part to incomplete knowledge of the effects of all of the invasive species present in the U.S. Estimates for the damages caused by well-known species can vary as well. The Office of Technology Assessment (OTA) has estimated zebra mussel economic effects at $300,000 a year, while an ACoE study put the number at $1 billion. The United States government spends an estimated $1 billion to recover from the invasive Formosan termite, investing $300 million of this budget is spent in areas surround New Orleans, a major port city. Estimates of total yearly costs due to invasive species range from $1.1 billion per year to $137 billion per year.

In 1993, the OTA estimated that a total of $100 million is invested annually in invasive species aquatic weed control in the US. Introduced rats cause more than $19 billion per year in damages, exotic fish cause up to $5.4 billion annually, and the total costs of introduced weeds are estimated at around $27 billion annually. The total damage to the U.S. native bird population due to invasive species is approximately $17 billion per year. Approximately $2.1 billion in forest products are lost each year to invasive plant pathogens in the United States, and a conservative estimate of the losses to U.S. livestock from exotic microbes and parasites was $9 billion per year in 2001.

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