By Kim Ghattas
BBC News, Washington
It is not yet known how many US embassies will issue invitations
For the first time since 1980, the US has authorised its embassies around the world to invite Iranian diplomats to Independence Day receptions.
The move is part of a new policy of engagement with Iran under President Barack Obama's administration.
The US is trying to convince Iran to end its nuclear ambitions.
It is still unclear how many embassies will send out invitations to the celebrations on 4 July and whether Iranian diplomats will attend.
The decision to invite Iranian diplomats to an American reception is a symbolic gesture but it puts an end to almost 30 years of a US policy discouraging even informal contacts with Iranian officials.
It is not yet known whether Iranians from Tehran's interest section in Washington will be invited to the 4 July reception at the State Department.
The two countries have no diplomatic relations and the ban on substantive discussions remains in place, but this 4 July American diplomats will be allowed to go beyond the courtesy handshake and engage in small talk with their Iranian counterparts.
The move is in line with the Obama administration's attempts to engage diplomatically with America's long-time foe.
Iran's reaction has been mixed so far and it has yet to respond to an offer of incentives from the US and its partners in return for stopping uranium enrichment.