The Federal Government provided blank printed forms to the U.S. Marshals.  There may be annotations such as certificates of oaths taken, population totals, and handwritten and mechanically-stamped page numbers.  The form consisted of two pages.

The law required "That every person whose usual place of abode shall be in any family on [June 1, 1840], shall be returned as of such family; and the name of every person, who shall be an inhabitant of any district or Territory, without a settled place of residence, shall be inserted in the column of the schedule which is allotted for the heads of families, in the division where he or she shall be on [June 1, 1840], and every person occasionally absent at the time of the enumeration, as belonging to that place in which he usually resides in the United States."

Secretary of State John Forsyth had general supervision of census operations and tabulating and reporting the results to the President and Congress.

The U.S. Marshal for each Federal judicial district was responsible for taking the census in his district with the help of assistant marshals whom he appointed.  Each marshal took an oath or affirmation that "I will truly and faithfully cause to be made a full and perfect enumeration and description of all persons resident within my district, (or territory,) and return the same to the Secretary of State, agreeably to the directions of an act of Congress, entitled, 'An act to provide for taking the sixth census or enumeration of the inhabitants of the United States,' according to the best of my ability."  Each assistant marshal took an oath or affirmation that "I will make a just, faithful, and perfect enumeration and description of all persons, resident within the division assigned to me for that purpose ... according to the best of my ability, and that I will take the said enumeration and description by actual inquiry at every dwelling house within said division, or personal inquiry of the head of every family, and not otherwise." 

Every person over age 16 was required to cooperate: "That each and every free person more than sixteen years of age, whether heads of families or not ... shall be, and hereby is, obliged to render to the assistant [marshal] ... if required, a true account, to the best of his or her knowledge, of every person belonging to such family ... on pain of forfeiting twenty dollars...."

The census began on Monday, June 1, 1840, and was finished within five months.

U.S. marshals conducted the 1840 census under the rules and directions established in an Act of Congress approved March 3, 1839, amended on February 26, 1840 and January 14, 1841. The two amendments corrected errors and omissions in the original act.

Names of Heads of Families

Free White Persons, including Heads of Families

• Males
  • Under 5 years of age
    
  • 5 and under 10 years of age
  • 10 and under 15 years of age
  • 15 and under 20 years of age
  • 20 and under 30 years of age
  • 30 and under 40 years of age
  • 40 and under 50 years of age
  • 50 and under 60 years of age
  • 60 and under 70 years of age
  • 70 and under 80 years of age
  • 80 and under 90 years of age
  • 90 and under 100 years of age
  • 100 years of age and upwards
     
• Females
  • Under 5 years of age
    
  • 5 and under 10 years of age
  • 10 and under 15 years of age
  • 15 and under 20 years of age
  • 20 and under 30 years of age
  • 30 and under 40 years of age
  • 40 and under 50 years of age
  • 50 and under 60 years of age
  • 60 and under 70 years of age
  • 70 and under 80 years of age
  • 80 and under 90 years of age
  • 90 and under 100 years of age
  • 100 years of age and upwards

Free Colored Persons

• Males
  • Under 10 years of age
  • 10 and under 24 years of age
  • 24 and under 36 years of age
  • 36 and under 55 years of age
  • 55 and under 100 years of age
  • 100 years of age and upwards
• Females
  • Under 10 years of age
  • 10 and under 24 years of age
  • 24 and under 36 years of age
  • 36 and under 55 years of age
  • 55 and under 100 years of age
  • 100 years of age and upwards

Slaves

• Males
  • Under 10 years of age
  • 10 and under 24 years of age
  • 24 and under 36 years of age
  • 36 and under 55 years of age
  • 55 and under 100 years of age
  • 100 years of age and upwards
• Females
  • Under 10 years of age
  • 10 and under 24 years of age
  • 24 and under 36 years of age
  • 36 and under 55 years of age
  • 55 and under 100 years of age
  • 100 years of age and upwards

Total (in each household)

Number of Persons in Each Family Employed in

• Mining
• Agriculture
• Commerce
• Manufactures and trades
• Navigation of the ocean
• Navigation of canals, lakes, and rivers
• Learned professions and engineers

Pensioners for Revolutionary or Military Services, included in the foregoing

• Name
• Ages

Deaf and Dumb, Blind, and Insane White Persons, included in the foregoing

• Deaf and Dumb
  • Under age 14
  • 14 and under 25 years of age
  • 25 years of age and upwards
• Blind and Insane
  • Blind
  • Insane and idiots at public charge
  • Insane and idiots at private charge

Deaf, Dumb, Blind, and Insane Colored Persons, included in the foregoing

• Deaf, Dumb and Blind
  • Deaf and Dumb
  • Blind
• Insane and Idiots
  • Insane and idiots at private charge
  • Insane and idiots at public charge

Schools, etc.

• Number of Universities or Colleges
• Number of Students
• Number of Academies & Grammar Schools
• Number of Students
• Number of Primary and Common Schools
• Number of Students
• Number of Scholars at public charge
• Number free white persons over 20 years of age who cannot read and write

The 1840 Census Act directed for collection of information on veterans, disabilities of the population, as well as number of persons attending educational institutions.

For the second time information was collected on number of persons employed in specific economic industries.

The act specifically stated:

That the aforesaid marshals and their assistants shall also take a census of all persons receiving pensions from the United States for revolutionary or military services, stating their names and ages : and also shall collect and return in statistical tables, under proper heads, according to such forms as shall be furnished, all such information in relation to mines, agriculture, commerce, manufactures, and schools, as will exhibit a full view of the pursuits, industry, education and reseurces of the country, as shall be directed by the President of the United States.