If you're looking for a State Constitution, you can often find links to the text online, for free, at the State's official website.
The Cornell Legal Information Institute (LII) has a list of links for the laws of all fifty states.
Click on the link to the State that you are researching, and it will take you to the State page.
The State page should include a direct link to a free viewing of the text of the State's Constitution.
You can view the list here.
The United States Constitution was created on September 17, 1787. You can find the text online at:
The first New York State Constitution was adopted on April 20, 1777. Since then, four subsequent Constitutions were adopted; the last in 1938 (which has been amended since then, but not replaced.) You can find the text on line at:
This highly valuable resource, first published in 1906, is a five volume treatise on New York State Constitutional History, authored by Charles Z. Lincoln. Within the five volumes, you will find the original text of each of the five adopted Constitutions, as well as other key documents and research resources for New York's Constitutional history. You can access this resource from a number of different resources:
KFN5681 .L56 1994 on the second floor of the library (print version)
KFN5681 .L5 1906 downstairs on the concourse (microform)
Digital copy: (You must be logged into a TLC Web account to access these databases.)
HeinOnline in its original print as a PDF
The Making of Modern Law: Legal Treatises 1800-1926 in its original print as a PDF
The T.C. Williams School of Law at the University of Richmond offers the Constitution Finder, which allows you to locate and read the text of Constitutions from countries around the world. The landing page allows you to view the original U.S. Constitution, in several different languages, here. To view foreign constitutions from around the world, after arriving at the database, click on "Reset All Filters." Click on the appropriate check box to the left if you are interested in a particular country's constitution. To view U.S. State Constitutions, after landing on the home page, uncheck the box to the left marked "National," and links to all available State Constitutions will be viewable.