Even long-time researchers are sometimes unaware that a few individual state and county census records do exist for 1890. Perhaps you've been looking for the 1850 U.S. Federal Census records for West Virginia? Wrong move. West Virginia didn't exist as a separate state until the Civil War, aka, War Between the States. You actually need to look in the Virginia census records.
Trying to do genealogy research without brushing up on your history, will lead you in circles and multiply the number of brick walls you hit. So, remember to check the formation date of the state you are searching, as there are no U.S. Federal Census records for a state prior to statehood. For example, the State of Alabama did not exist in 1790, 1800 or 1810, so federal records for that state start in 1820.
However, the area that is now Alabama was enumerated in 1810 as part of Mississippi Territory. Although there may be an exception of which I am not aware, in addition to most 1890 census records, you will most likely not be able to find complete individual federal census records, or there is some other "caveat," for the following:
Alabama, 1810 (was part of Mississippi Territory), 1820 (about half of the counties are missing)
Alaska Territory 1870
Arkansas Territory, 1820, 1860 includes non-Indians in Indian Territory except Little River County is missing)
Arizona 1860 (see New Mexico Territory)
Colorado 1860 (See Utah Territory)
District of Columbia, 1810
Delaware, 1790, 1800
Georgia, 1790, 1800 (Oglehorpe County only), 1810
Illinois, 1800 (and in 1810 only Randolph County is available.)
Indiana, 1800, 1810 (includes Michigan Territory), 1820 (Davies
County is missing)
Indian Territory 1860 (includes non-Indians only and is included in Arkansas census)
Kentucky, 1790, 1800, 1890 (partial list only)
Louisiana Territory 1810
Maryland 1830 (missing five counties)
Massachusetts 1830 (missing most of Suffolk County)
Michigan, 1810, 1820 (see Indiana)
Minnesota 1830 (included in Michigan Territory)
Mississippi Territory, 1800, 1810 (including Alabama), 1830 (Pike County is missing)
Missouri Territory, 1810 (was part of Louisiana Territory), 1820
Montana area 1860 (included in Washington Territory as "Bitterroot Valley and some parts in Nebraska Territory records.)
Nebraska Territory 1860 (includes areas that are now CO, WY, MT, ND, and SD.)
Nevada 1860 (See Utah Territory)
New Jersey, 1790, 1800 (Cumberland County only), 1810, 1820
New Mexico Territory 1860 (includes Arizona
New York City 1870 (Separate from New York state and includes Suffolk, Co.)
North Carolina, part of 1790, 1810, and 1830
Ohio, 1810 (only Washington County is available)
Tennessee, 1800, 1810, 1820 (about a third is missing --- eastern part of the state)
Utah Territory 1860 (includes areas that are now NV, CO, and WA)
Virginia, 1790, 1800
Washington Territory 1860 (Includes part of what is now ID, western MT and WY; but, part of what is now Washington state was enumerated in Utah Territory)
Wisconsin 1820 (included in Michigan Territory)
Wyoming 1860 (See Nebraska Territory)
Some missing state data has been re-created using tax lists and can be found on Broderbund CDs and books published by Heritage Quest (formerly the American Genealogical Lending Library.). For access check with your local library or Family History Center (FHC).
As you may have noted from the above list, in 1860 census records were taken for Washington, Nebraska and Kansas Territories, as well as the "Unorganized Dakota" Territory. A census was taken for the first time in Oklahoma Territory--also known as Indian Territory--but only non-Indians were enumerated.
The name lists for the "non-Indians" were added to the end of the Arkansas census. In 1870, the Indian Territory was not enumerated.
One type of 1890 census records that is available on a federal level is a special Veterans and Widows of Union Veterans census that was extracted from the original records. And even this one is not complete because records from 16 states and territories were reported lost. They were apparently filed alphabetically with A through most of K being lost. The remaining information includes approximately half of Kentucky and the remainder of the states and territories down through the alphabet to Wyoming.
In general, census data was complied by states and/or territories; the originals were then sent to the federal government and are maintained in the National Archives. The exceptions to this are shown in the above list. In addition, the 1880 census records were copied and then the originals were returned to state archives, state libraries, and even some genealogical societies. The original 1900, 1910 and 1920 records were destroyed after microfilming--copies are all that is left. Whenever possible, always try to view original copies. Transcriptions, as we all known, are prone to error.