The results of the census are used to allocate funds and Congressional seats
The 2010 US census reaches a climax on Thursday with Census Day, the deadline for all households in the country to return their census form.
More than 50% of people have already returned their form, but the government is looking to boost that number with a series of rallies across the country.
The census results are used to allocate federal funds and congressional seats.
Hispanics, who in the past have shunned the count, have been targeted in adverts to ensure they respond.
This week, several regions are being urged to step up their response, including five states with higher shares of minority or indigenous populations that ranked at the bottom: Alaska, New Mexico, Louisiana, New York and Texas.
Some $400bn (£251bn) of federal money is allocated according to the population in each of the country's 50 states, as well as the number of each state's seats in the US House of Representatives.
US households were sent a 10-question form in March, which includes questions on how many people live in one household, who they are and what type of home they live in.
There are an estimated 12 million people who are in the US without the right legal documents, eight million of whom are thought to be Hispanic.
Many fear if they fill out the census, the information will be given to the immigration service and they will be deported.
But nearly nine out of every 10 Hispanics intend to participate in the census, according to a survey released by the Pew Hispanic Center on Thursday.
Overall, about 85% of Hispanics say they have already sent their census form or will definitely do so.
But among immigrants, the rate increases to 91%, compared to 78% for US-born Hispanics.
So immigrants were more likely to say the government count was good for their community and that personal information would be kept confidential, the poll said.
The Census Bureau has been reinforcing that message, with TV adverts aimed at the Hispanic community, emphasising people's private information will not be shared.
But the National Coalition of Latino Clergy and Christian Leaders (Conlamic), which says it represents 20,000 churches in 34 states, has suggested a Hispanic boycott of the census to protest against the lack of action on immigration.
The Census Bureau will continue to accept posted forms for the rest of the month, and from May until July will send census takers to households that have not replied.
This is the 23rd edition of the census, which has been held every 10 years since 1790.