Wednesday saw the most-intense day of demonstrations, reaching rural towns and major cities in every province though still localised enough for daily life to continue in Tehran, Iran's capital, and elsewhere.
Violence around the demonstrations has killed at least 38 people while more than 2200 others have been detained, said the US-based Human Rights Activists News Agency.
The growth of the protests increases the pressure on Iran's civilian government and its Supreme Leader Ayatollah Ali Khamenei.
So far, authorities have not shut down the internet or fully flooded the streets with security forces like they did to put down the 2022 Mahsa Amini demonstrations.
But any intensification might seem them act.
Meanwhile, the protests themselves have remained broadly leaderless, though a call for protests by Iran's exiled crown prince will test whether or not demonstrators are being swayed by messages from abroad.
On Wednesday, at least 37 protests took place across the country, activists said.
They included Shiraz, where online videos purported to show an anti-riot truck using a water cannon to target demonstrators.
The state-run IRNA news agency, which has largely been silent about the demonstrations, reported on a mass demonstration in Bojnourd, as well as demonstrations in Kerman and Kermanshah.
Iranian officials have offered no acknowledgment of the scale of the protests.
However, there has been reporting regarding security officials being hurt or killed.
The judiciary's Mizan news agency report a police colonel suffered fatal stab wounds in a town outside of Tehran, while the semi-official Fars news agency said gunmen killed two security force members and wounded 30 others in a shooting in the city of Lordegan in Chaharmahal and Bakhtiari province.
Demonstrations continued on Thursday, with merchants closing their shops in Iran's Kurdistan province.
It remains unclear why Iranian officials have yet to crack down harder on the demonstrators.
US President Donald Trump's warned last week that if Tehran "violently kills peaceful protesters", America "will come to their rescue".
Trump's comments drew a new rebuke from Iran's foreign ministry.
"Recalling the long history of criminal interventions by successive US administrations in Iran's internal affairs, the foreign ministry considers claims of concern for the great Iranian nation to be hypocritical, aimed at deceiving public opinion and covering up the numerous crimes committed against Iranians," it said.
As sanctions tightened and Iran struggled after a 12-day war with Israel in June, its rial currency collapsed in December, reaching 1.4 million to $US1.
Protests began soon after, with demonstrators chanting against Iran's theocracy.
