Until the 1880s the length of service of the average senator and representative remained at a low and fairly constant level -- representatives averaged two years (after a higher level of around three years during a peak of House influence on national policy in the 1810s and 1820s) and Senators around four years. Members of both chambers, especially the House, routinely left Congress for other opportunities, both governmental and private. Mid-term resignations were common.
Beginning about 1880 the average years of service rose dramatically in both houses, doubling in the Senate [to eight years] in less than two decades and almost tripling in the House [to six years] in three decades. The upward trend continued, with breaks for political turnovers, until the late 1960s.
The Senate filibuster wasn't established as a procedural tool in the the U.S. Senate until 1841. They were very rare until the 1960s and used mostly to block civil rights legislation.
Until the 17th Amendment to the United States Constitution was adopted in 1913, U.S. Senators were appointed by state legislatures, not elected, an appointment that almost always reflected the state legislature's political makeup. The U.S. Senate also started small, initially having only twenty-six members.
Elections back then were questionable things in any case. From 1789 to 1908 the House of Representatives resolved 382 contested elections (keep in mind that the House of Representatives started out with just 65 members), of which only three were given to the minority party candidate in the House. Since 1910, House of Representatives resolution of contested elections has grown much more rare, and state elections officials and courts almost always resolve the disputes before the House acts.
At first, only men could vote outside New Jersey (the 19th Amendment gave women the right to vote nationwide in 1920). Women weren't the only ones disenfranchised:
During the Revolution states with poll taxes and taxpayer franchises (such as North Carolina and New Hampshire) established nearly universal free male suffrage. When suffrage qualifications were tied to the value of an estate, wartime inflation eroded barriers. All states ended religious restrictions on voting. At war's end, the eligible electorate numbered from 60 to 90 percent of free males, with most states edging close to the high end of that range. . . .Between 1790 and 1860 almost every state, old and new, disfranchised free blacks while expanding the electorate to include almost all white adult male citizens.
The suffrage requirements of the frontier states were more democratic than eastern ones. Beginning with Kentucky in 1792, all but two western states embraced white male adult suffrage; in the East, all but two states retained either a property or taxpaying qualification for all or part of the period from 1820 to 1860. Several western states even enfranchised aliens who had established permanent residence and Indians who had given up tribal citizenship. . . .
[The] Rhode Island . . . requirement that a man own a $134 freehold in order to vote became increasingly restrictive as the Rhode Island economy shifted from agriculture toward industry. By the early 1840s more than half of the state's male population was disfranchised. But a reform effort led by Thomas Dorr, after holding an extralegal constitutional convention in 1841 and an extralegal gubernatorial election, sparked some liberalization of suffrage requirements. . . .
Black male suffrage became national in 1870 when the Fifteenth Amendment prohibited states from discriminating against potential voters because of race or previous condition of servitude (but not sex). . . . For most of Reconstruction, blacks voted and often used their resulting political power to protect their other rights. Although white Democrats overthrew Reconstruction by forcibly keeping blacks from the polls, thereafter they generally eschewed violence. Instead, they relied upon discriminatory apportionment and election laws to limit black and poor white political influence, and in the 1890s and 1900s, imposed poll taxes and literacy and property requirements through constitutional revisions. Thus they disfranchised virtually all black men and many poor whites, and thereby ensured Democratic hegemony.
Your vote was a public matter. The secret ballot was an innovation of the Progressive era:
In the United States, most states had moved to secret ballots soon after the presidential election of 1884. However, Kentucky was the last state to do so in 1891, when it quit using an oral ballot. Therefore, the first President of the United States elected completely under the Australian ballot was president Grover Cleveland in 1892.
Often an entire state's Congressional delegation was elected at large:
[M]ost of the original thirteen states used multi-member districts in the first congressional elections . . .
Congress passed a series of apportionment acts, primarily after each decennial census and representatives were added to the House as new states were admitted to the Union, but Congress remained silent as to the ways in which the states elected their representatives. In 1842, six states were electing representatives at-large and twenty-two states were electing representatives by single-member district. Three states had only one representative. This arrangement changed with an apportionment act in 1842 (5 Stat. 491). This act set the House membership at 223 members and contained a requirement for single-member districts. . . . In the first election after the passage of the 1842 act four states -- Georgia, Mississippi, Missouri, and New Hampshire -- continued to elect representatives at-large rather than by districts.
The members of Congress elected in those states were seated and the constitutionality of the 1842 act was questioned by the House committee resolving the credentials dispute.
An apportionment act passed in 1850 (9 Stat. 433) increased the size of the House to 233 but dropped provisions requiring elections by districts. However, an act in 1862 (12 Stat. 572) restored the provisions of the act of 1842 requiring districts composed of contiguous territory.
An apportionment act in 1872 (17 Stat. 28) again reiterated the requirement of districts composed of contiguous territory and added that they should contain "as nearly as practicable an equal number of inhabitants." The apportionment act of 1882 (22 Stat. 5) and an act in 1891 repeated the provisions of contiguous territory and equal population of the 1872 act. An apportionment act in 1901 (31 Stat. 733) added that districts should not only be of equal population and contiguous but also be of "compact territory." These provisions were also included in 1911's apportionment act (37 Stat. 13).
In 1929 Congress passed a combined census-reapportionment bill which established a permanent method for apportioning House seats according to each census. This bill neither repealed nor restated the requirements of the previous apportionment acts -- that districts be contiguous, compact, and equally populated.
It was not clear if these requirements were still in effect until the Supreme Court ruled in 1932 in Wood v. Broom that the provisions of each apportionment act affected only the apportionment for which they were written. Thus the size and population requirements, last stated in the act of 1911, expired immediately with the enactment of the subsequent apportionment act. . . . [This] allowed states to abandon districts altogether and elect at least some representatives at large, which several states chose to do, including New York, Illinois, Washington, Hawaii and New Mexico. In the 88th Congress (in the early 1960s), for example, 22 of the 435 representatives were elected at-large.
In 1967 Congress passed a law (PL 90-196) which prohibited at-large and other multi-member elections by states with more than one House seat. Only two states, Hawaii and New Mexico, were affected by this legislation: all other states by this time were using elections by districts.
Sessions of Congress were in any case short; they had little to do. The first Congress met seventeen months out of twenty-four implementing the new constitution. the Civil War and Reconstruction Congresses met between ten and twenty-two months. In every other two year session of Congress until the one commencing in 1911, Congress met for less than twelve of the twenty-four months of the session.
And, the House of Representatives was a tough place. In the 19th century, physical violence on the House floor was not infrequent and guns and knives were occasional carried onto the floor.