Six people were injured by the devices
Luke Helder - who had been described as "armed and dangerous" by the Federal Bureau of Investigation - was arrested after his car was spotted by a motorist in the town of Lovelock, Nevada.
The two charges relate to a bomb that exploded in Iowa on 3 May, injuring a woman.
"This was an incident of national concern which received a national response," US Attorney Charles Larson of the Northern District of Iowa told Reuters news agency.
"The involvement of the public and hundreds of law enforcement agents led to the successful arrest this evening."
'Domestic terrorism'
Mr Helder, originally from Minnesota, reportedly threw a gun out of his car window shortly before his capture.
Police were called to check for further explosive devices in his car.
Eighteen pipe bombs had been found in mailboxes in Nebraska, Colorado, Iowa, Texas and Illinois since last Friday.
Six people were injured by the devices, although none were seriously hurt.
Federal government officials had described the bombings as "acts of domestic terrorism", and said notes had been found nearby warning of further "attention getters".
Most of the bombs reportedly contained similar anti-government notes signed by "someone who cares" and which complained about limits imposed on personal freedom.
Mr Helder's father had pleaded with his son to turn himself over to authorities.
"Please don't hurt anyone else. ... You have the attention you wanted," he said.
Latest attack
In recent years, the United States has seen several acts of terrorism carried out by its own citizens.
In 1998, Theodore Kaczynski, known as the Unabomber, was sentenced to four terms of life in prison without parole for a 17-year bombing spree which left three people dead and many injured.
Last June, Gulf War veteran Timothy McVeigh was executed for the 1995 bombing of a federal building in Oklahoma that killed 168 people and injured hundreds of others.
Following the 11 September attacks on the US, the country was hit by a series of anthrax attacks which the FBI believes was probably the work of a US national.